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Re: "Yellow Box Coater"

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  • radroy92
    Why do we have to use heavy emmitters like that can we use thinner wire? Or does it fall apart at those temperatures? Roy M. ... they ... think ... emmitter
    Message 1 of 21 , Jul 1, 2008
      Why do we have to use heavy emmitters like that can we use thinner
      wire? Or does it fall apart at those temperatures?

      Roy M.



      --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
      AEROSPACE]" <andrew.n.aurigema@...> wrote:
      >
      > Get a big variac for that. I burned up a 1kw unit discovering that
      they
      > are not rated to what they say they can take. go twice what you
      think
      > you need. You know you need a serious stepdown transformer to make
      > lots of amps at low voltage ( like 30 amps at 3 vac for each
      emmitter ).
      >
      >
      > I just chatted with James a few minutes ago so I know he is at least
      > typing. He may not be monitoring this list right now.
      >
      > Andrew in sunny FLA
      >
      >
      >
      > ________________________________
      >
      > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On
      Behalf
      > Of radroy92
      > Sent: Monday, June 30, 2008 12:53 PM
      > To: VacuumX@yahoogroups.com
      > Subject: [VacuumX] Re: "Yellow Box Coater"
      >
      >
      >
      > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com> ,
      > "glinos7124" <tg@> wrote:
      > >
      > >
      > > Does anyone have any details on the Lerch/Jones box coater
      > > at the St. Petersburg Mirror Lab?
      > >
      > > Dimensions, materials, pumps, sensors,.... that kind of thing.
      > >
      > > I'm mulling over building one.
      > > It looks like a challenging, but doable project.
      > >
      > > tom
      > >
      >
      > By they way I'm working on a similar project. I have almost
      everything
      > and I'm hooking up power for my new TIG welder so I can assemble
      some
      > of the parts. I have purchased most of the parts from eBay and the
      rest
      > came from the local Menards, a surplus metal supplier and some
      dumpster
      > diving. I'm currently on the tail end of cleaning my ancient NRC 4"
      > diff. pump. Looks like somebody let it overheat and part of the
      > aluminum splash shield was fused to the bottom of the pump. For my
      > initial chamber I have sectioned a 12" compressor tank and
      purchased an
      > angle flange from McMaster Carr to use in forming the sealing
      surface
      > at the open end. I have a small welder that I'm planning on using
      to
      > power the evap. coils and will controll it with a Variac.
      >
      > Roy M.
      >
    • Aurigema, Andrew N. (KSC)[ASRC AEROSPACE]
      You can use single wire emmitters. James does. his emmitters are about 1mm diameter bent into a U shape. I bought the tri-wire ones that are pre twisted so
      Message 2 of 21 , Jul 1, 2008
        You can use single wire emmitters.  James does.  his emmitters are about 1mm diameter bent into a U shape.  I bought the tri-wire ones that are pre twisted so i could put more aluminum on each strand.  I only have 24 emmitters and have to cover a 60" diameter disk so I needed to put out some serious material.  You cant put to much aluminunm on each wire or the tungston disolves into the aluminum and you eat up the wires.  So I put 3 wires on each emmitter with three little strips of aluminum ( about 60 mg total ) and zap it with lots of current.  
         
        Andrew 


        From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On Behalf Of radroy92
        Sent: Tuesday, July 01, 2008 2:07 PM
        To: VacuumX@yahoogroups.com
        Subject: [VacuumX] Re: "Yellow Box Coater"

        Why do we have to use heavy emmitters like that can we use thinner
        wire? Or does it fall apart at those temperatures?

        Roy M.

        --- In VacuumX@yahoogroups .com, "Aurigema, Andrew N. (KSC)[ASRC
        AEROSPACE]" <andrew.n.aurigema@ ...> wrote:

        >
        > Get a big variac for
        that. I burned up a 1kw unit discovering that
        they
        > are not rated to
        what they say they can take. go twice what you
        think
        > you need. You
        know you need a serious stepdown transformer to make
        > lots of amps at low
        voltage ( like 30 amps at 3 vac for each
        emmitter ).
        >
        >
        > I just chatted with James a few minutes ago so I know he is at
        least
        > typing. He may not be monitoring this list right now.
        >
        > Andrew in sunny FLA
        >
        >
        >
        >
        ____________ _________ _________ __
        >
        > From:
        href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com [mailto:VacuumX@yahoogroups .com] On
        Behalf
        > Of radroy92
        > Sent: Monday, June 30, 2008 12:53
        PM
        > To:
        href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com
        >
        Subject: [VacuumX] Re: "Yellow Box Coater"
        >
        >
        >
        >
        --- In VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com> ,
        > "glinos7124"
        <tg@> wrote:
        > >
        > >
        > > Does anyone have any
        details on the Lerch/Jones box coater
        > > at the St. Petersburg Mirror
        Lab?
        > >
        > > Dimensions, materials, pumps, sensors,.... that
        kind of thing.
        > >
        > > I'm mulling over building one.
        > > It looks like a challenging, but doable project.
        > >
        > >
        tom
        > >
        >
        > By they way I'm working on a similar project.
        I have almost
        everything
        > and I'm hooking up power for my new TIG
        welder so I can assemble
        some
        > of the parts. I have purchased most
        of the parts from eBay and the
        rest
        > came from the local Menards, a
        surplus metal supplier and some
        dumpster
        > diving. I'm currently on
        the tail end of cleaning my ancient NRC 4"
        > diff. pump. Looks like
        somebody let it overheat and part of the
        > aluminum splash shield was
        fused to the bottom of the pump. For my
        > initial chamber I have
        sectioned a 12" compressor tank and
        purchased an
        > angle flange from
        McMaster Carr to use in forming the sealing
        surface
        > at the open
        end. I have a small welder that I'm planning on using
        to
        > power the
        evap. coils and will controll it with a Variac.
        >
        > Roy
        M.
        >

      • radroy92
        How many emitters would I need for a 12.5 mirror?? I checked my litle welder I m planning on using for a supply for the emmitters. My Variac was putting out
        Message 3 of 21 , Jul 1, 2008
          How many emitters would I need for a 12.5 mirror??

          I checked my litle welder I'm planning on using for a supply for the
          emmitters. My Variac was putting out 13 Amps at 120 Volts. The
          welder was putting out 30 Amps at 30 Volts. This was with a 3.5 "
          long coil of 3/32 stainless wire that measured 1.1 ohm. It was
          glowing yellow hot laying on the concrete. Any more and it would
          melt. It fused to the concrete and a few spots.

          Roy M.


          --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
          AEROSPACE]" <andrew.n.aurigema@...> wrote:
          >
          > You can use single wire emmitters. James does. his emmitters are
          about
          > 1mm diameter bent into a U shape. I bought the tri-wire ones that
          are
          > pre twisted so i could put more aluminum on each strand. I only
          have 24
          > emmitters and have to cover a 60" diameter disk so I needed to put
          out
          > some serious material. You cant put to much aluminunm on each wire
          or
          > the tungston disolves into the aluminum and you eat up the wires.
          So I
          > put 3 wires on each emmitter with three little strips of aluminum (
          > about 60 mg total ) and zap it with lots of current.
          >
          > Andrew
          >
          > ________________________________
          >
          > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On
          Behalf
          > Of radroy92
          > Sent: Tuesday, July 01, 2008 2:07 PM
          > To: VacuumX@yahoogroups.com
          > Subject: [VacuumX] Re: "Yellow Box Coater"
          >
          >
          >
          > Why do we have to use heavy emmitters like that can we use thinner
          > wire? Or does it fall apart at those temperatures?
          >
          > Roy M.
          >
          > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com> ,
          > "Aurigema, Andrew N. (KSC)[ASRC
          > AEROSPACE]" <andrew.n.aurigema@> wrote:
          > >
          > > Get a big variac for that. I burned up a 1kw unit discovering
          that
          > they
          > > are not rated to what they say they can take. go twice what you
          > think
          > > you need. You know you need a serious stepdown transformer to make
          > > lots of amps at low voltage ( like 30 amps at 3 vac for each
          > emmitter ).
          > >
          > >
          > > I just chatted with James a few minutes ago so I know he is at
          least
          > > typing. He may not be monitoring this list right now.
          > >
          > > Andrew in sunny FLA
          > >
          > >
          > >
          > > ________________________________
          > >
          > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
          > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
          40yahoogroups.com> ] On
          > Behalf
          > > Of radroy92
          > > Sent: Monday, June 30, 2008 12:53 PM
          > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
          > > Subject: [VacuumX] Re: "Yellow Box Coater"
          > >
          > >
          > >
          > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
          > <mailto:VacuumX%40yahoogroups.com> ,
          > > "glinos7124" <tg@> wrote:
          > > >
          > > >
          > > > Does anyone have any details on the Lerch/Jones box coater
          > > > at the St. Petersburg Mirror Lab?
          > > >
          > > > Dimensions, materials, pumps, sensors,.... that kind of thing.
          > > >
          > > > I'm mulling over building one.
          > > > It looks like a challenging, but doable project.
          > > >
          > > > tom
          > > >
          > >
          > > By they way I'm working on a similar project. I have almost
          > everything
          > > and I'm hooking up power for my new TIG welder so I can assemble
          > some
          > > of the parts. I have purchased most of the parts from eBay and
          the
          > rest
          > > came from the local Menards, a surplus metal supplier and some
          > dumpster
          > > diving. I'm currently on the tail end of cleaning my ancient NRC
          4"
          > > diff. pump. Looks like somebody let it overheat and part of the
          > > aluminum splash shield was fused to the bottom of the pump. For
          my
          > > initial chamber I have sectioned a 12" compressor tank and
          > purchased an
          > > angle flange from McMaster Carr to use in forming the sealing
          > surface
          > > at the open end. I have a small welder that I'm planning on using
          > to
          > > power the evap. coils and will controll it with a Variac.
          > >
          > > Roy M.
          > >
          >
        • Aurigema, Andrew N. (KSC)[ASRC AEROSPACE]
          That is what is going to take you a lot of time to figure out. You can use a lot of emmitters ( 18 or so ) close up ( a few inches away ) or a lesser number
          Message 4 of 21 , Jul 2, 2008
            That is what is going to take you a lot of time to figure out.  You can use a lot of emmitters ( 18 or so ) close up ( a few inches away  )  or a lesser number farther back.  In theory you could put one at the focal point of the mirror and it would give you the best overall coating.  But you will need a long chamber with very very good vacuum for that. 
             
            Not sure how you are using a variac and welder at the same time. 
             
            I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts stepdown transformer.  the 24 vac is just right to power 4 tungstens in series.  It took me a lot of experimentation to get the right number of emmitters in series and parallel for my power supplies.  Now I can start out cherry red to wick the aluminum onto the tungsten then go to near white hot for a few seconds then back to cherry and then off.  If you hit the power to fast the aluminum just melts and falls.  that is very very very bad for you mirror so dont ever let that happen.    
             
            Andrew


            From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On Behalf Of radroy92
            Sent: Tuesday, July 01, 2008 5:36 PM
            To: VacuumX@yahoogroups.com
            Subject: [VacuumX] Re: "Yellow Box Coater"

            How many emitters would I need for a 12.5 mirror??

            I checked my litle welder I'm planning on using for a supply for the
            emmitters. My Variac was putting out 13 Amps at 120 Volts. The
            welder was putting out 30 Amps at 30 Volts. This was with a 3.5 "
            long coil of 3/32 stainless wire that measured 1.1 ohm. It was
            glowing yellow hot laying on the concrete. Any more and it would
            melt. It fused to the concrete and a few spots.

            Roy M.

            --- In VacuumX@yahoogroups .com, "Aurigema, Andrew N. (KSC)[ASRC
            AEROSPACE]" <andrew.n.aurigema@ ...> wrote:

            >
            > You can use single
            wire emmitters. James does. his emmitters are
            about
            > 1mm diameter
            bent into a U shape. I bought the tri-wire ones that
            are
            > pre twisted
            so i could put more aluminum on each strand. I only
            have 24
            >
            emmitters and have to cover a 60" diameter disk so I needed to put
            out
            > some serious material. You cant put to much aluminunm on each
            wire
            or
            > the tungston disolves into the aluminum and you eat up the
            wires.
            So I
            > put 3 wires on each emmitter with three little strips of
            aluminum (
            > about 60 mg total ) and zap it with lots of current.
            >
            > Andrew
            >
            >
            ____________ _________ _________ __
            >
            > From:
            href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com [mailto:VacuumX@yahoogroups .com] On
            Behalf
            > Of radroy92
            > Sent: Tuesday, July 01, 2008 2:07
            PM
            > To:
            href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com
            >
            Subject: [VacuumX] Re: "Yellow Box Coater"
            >
            >
            >
            >
            Why do we have to use heavy emmitters like that can we use thinner
            >
            wire? Or does it fall apart at those temperatures?
            >
            > Roy
            M.
            >
            > --- In
            href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com> ,
            > "Aurigema, Andrew
            N. (KSC)[ASRC
            > AEROSPACE]" <andrew.n.aurigema@ >
            wrote:
            > >
            > > Get a big variac for that. I burned up a 1kw
            unit discovering
            that
            > they
            > > are not rated to what they
            say they can take. go twice what you
            > think
            > > you need. You
            know you need a serious stepdown transformer to make
            > > lots of amps
            at low voltage ( like 30 amps at 3 vac for each
            > emmitter ).
            > >
            > >
            > > I just chatted with James a few minutes ago so
            I know he is at
            least
            > > typing. He may not be monitoring this
            list right now.
            > >
            > > Andrew in sunny FLA
            > >
            > >
            > >
            > >
            ____________ _________ _________ __
            > >
            > > From:
            VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
            > [mailto:
            href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX%
            40yahoogroups. com> ] On
            > Behalf
            > > Of radroy92
            > > Sent: Monday, June 30, 2008 12:53 PM
            > >
            To: VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
            > > Subject:
            [VacuumX] Re: "Yellow Box Coater"
            > >
            > >
            > >
            > > --- In
            href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
            >
            <mailto:VacuumX% 40yahoogroups. com> ,
            > > "glinos7124"
            <tg@> wrote:
            > > >
            > > >
            > > > Does
            anyone have any details on the Lerch/Jones box coater
            > > > at the
            St. Petersburg Mirror Lab?
            > > >
            > > > Dimensions,
            materials, pumps, sensors,.... that kind of thing.
            > > >
            > > > I'm mulling over building one.
            > > > It looks like a
            challenging, but doable project.
            > > >
            > > >
            tom
            > > >
            > >
            > > By they way I'm working on a
            similar project. I have almost
            > everything
            > > and I'm hooking
            up power for my new TIG welder so I can assemble
            > some
            > > of
            the parts. I have purchased most of the parts from eBay and
            the
            >
            rest
            > > came from the local Menards, a surplus metal supplier and
            some
            > dumpster
            > > diving. I'm currently on the tail end of
            cleaning my ancient NRC
            4"
            > > diff. pump. Looks like somebody let
            it overheat and part of the
            > > aluminum splash shield was fused to
            the bottom of the pump. For
            my
            > > initial chamber I have
            sectioned a 12" compressor tank and
            > purchased an
            > > angle
            flange from McMaster Carr to use in forming the sealing
            > surface
            > > at the open end. I have a small welder that I'm planning on using
            > to
            > > power the evap. coils and will controll it with a
            Variac.
            > >
            > > Roy M.
            > >
            >

          • radroy92
            Hi Andrew, The welder I want to use is a little Sears carbon arc/stick welder with a max output of 50 Amps at 45 volts or so. It runs on 120 Volts so I just
            Message 5 of 21 , Jul 2, 2008
              Hi Andrew,

              The welder I want to use is a little Sears carbon arc/stick welder
              with a max output of 50 Amps at 45 volts or so. It runs on 120 Volts
              so I just plugged it into a 10 Amp Variac.

              Can Nichrome wire be used for emitters??

              Roy M.






              --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
              AEROSPACE]" <andrew.n.aurigema@...> wrote:
              >
              > That is what is going to take you a lot of time to figure out. You
              can
              > use a lot of emmitters ( 18 or so ) close up ( a few inches
              away ) or
              > a lesser number farther back. In theory you could put one at the
              focal
              > point of the mirror and it would give you the best overall
              coating. But
              > you will need a long chamber with very very good vacuum for that.
              >
              > Not sure how you are using a variac and welder at the same time.
              >
              > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts stepdown
              > transformer. the 24 vac is just right to power 4 tungstens in
              series.
              > It took me a lot of experimentation to get the right number of
              emmitters
              > in series and parallel for my power supplies. Now I can start out
              > cherry red to wick the aluminum onto the tungsten then go to near
              white
              > hot for a few seconds then back to cherry and then off. If you hit
              the
              > power to fast the aluminum just melts and falls. that is very very
              very
              > bad for you mirror so dont ever let that happen.
              >
              > Andrew
              >
              > ________________________________
              >
              > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On
              Behalf
              > Of radroy92
              > Sent: Tuesday, July 01, 2008 5:36 PM
              > To: VacuumX@yahoogroups.com
              > Subject: [VacuumX] Re: "Yellow Box Coater"
              >
              >
              >
              > How many emitters would I need for a 12.5 mirror??
              >
              > I checked my litle welder I'm planning on using for a supply for
              the
              > emmitters. My Variac was putting out 13 Amps at 120 Volts. The
              > welder was putting out 30 Amps at 30 Volts. This was with a 3.5 "
              > long coil of 3/32 stainless wire that measured 1.1 ohm. It was
              > glowing yellow hot laying on the concrete. Any more and it would
              > melt. It fused to the concrete and a few spots.
              >
              > Roy M.
              >
              > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com> ,
              > "Aurigema, Andrew N. (KSC)[ASRC
              > AEROSPACE]" <andrew.n.aurigema@> wrote:
              > >
              > > You can use single wire emmitters. James does. his emmitters are
              > about
              > > 1mm diameter bent into a U shape. I bought the tri-wire ones that
              > are
              > > pre twisted so i could put more aluminum on each strand. I only
              > have 24
              > > emmitters and have to cover a 60" diameter disk so I needed to
              put
              > out
              > > some serious material. You cant put to much aluminunm on each
              wire
              > or
              > > the tungston disolves into the aluminum and you eat up the wires.
              > So I
              > > put 3 wires on each emmitter with three little strips of aluminum
              (
              > > about 60 mg total ) and zap it with lots of current.
              > >
              > > Andrew
              > >
              > > ________________________________
              > >
              > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
              40yahoogroups.com> ] On
              > Behalf
              > > Of radroy92
              > > Sent: Tuesday, July 01, 2008 2:07 PM
              > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > > Subject: [VacuumX] Re: "Yellow Box Coater"
              > >
              > >
              > >
              > > Why do we have to use heavy emmitters like that can we use
              thinner
              > > wire? Or does it fall apart at those temperatures?
              > >
              > > Roy M.
              > >
              > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > <mailto:VacuumX%40yahoogroups.com> ,
              > > "Aurigema, Andrew N. (KSC)[ASRC
              > > AEROSPACE]" <andrew.n.aurigema@> wrote:
              > > >
              > > > Get a big variac for that. I burned up a 1kw unit discovering
              > that
              > > they
              > > > are not rated to what they say they can take. go twice what you
              > > think
              > > > you need. You know you need a serious stepdown transformer to
              make
              > > > lots of amps at low voltage ( like 30 amps at 3 vac for each
              > > emmitter ).
              > > >
              > > >
              > > > I just chatted with James a few minutes ago so I know he is at
              > least
              > > > typing. He may not be monitoring this list right now.
              > > >
              > > > Andrew in sunny FLA
              > > >
              > > >
              > > >
              > > > ________________________________
              > > >
              > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > <mailto:VacuumX%40yahoogroups.com>
              > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > <mailto:VacuumX%
              > 40yahoogroups.com> ] On
              > > Behalf
              > > > Of radroy92
              > > > Sent: Monday, June 30, 2008 12:53 PM
              > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
              > <mailto:VacuumX%40yahoogroups.com>
              > > > Subject: [VacuumX] Re: "Yellow Box Coater"
              > > >
              > > >
              > > >
              > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
              40yahoogroups.com>
              > <mailto:VacuumX%40yahoogroups.com>
              > > <mailto:VacuumX%40yahoogroups.com> ,
              > > > "glinos7124" <tg@> wrote:
              > > > >
              > > > >
              > > > > Does anyone have any details on the Lerch/Jones box coater
              > > > > at the St. Petersburg Mirror Lab?
              > > > >
              > > > > Dimensions, materials, pumps, sensors,.... that kind of thing.
              > > > >
              > > > > I'm mulling over building one.
              > > > > It looks like a challenging, but doable project.
              > > > >
              > > > > tom
              > > > >
              > > >
              > > > By they way I'm working on a similar project. I have almost
              > > everything
              > > > and I'm hooking up power for my new TIG welder so I can
              assemble
              > > some
              > > > of the parts. I have purchased most of the parts from eBay and
              > the
              > > rest
              > > > came from the local Menards, a surplus metal supplier and some
              > > dumpster
              > > > diving. I'm currently on the tail end of cleaning my ancient
              NRC
              > 4"
              > > > diff. pump. Looks like somebody let it overheat and part of the
              > > > aluminum splash shield was fused to the bottom of the pump. For
              > my
              > > > initial chamber I have sectioned a 12" compressor tank and
              > > purchased an
              > > > angle flange from McMaster Carr to use in forming the sealing
              > > surface
              > > > at the open end. I have a small welder that I'm planning on
              using
              > > to
              > > > power the evap. coils and will controll it with a Variac.
              > > >
              > > > Roy M.
              > > >
              > >
              >
            • Aurigema, Andrew N. (KSC)[ASRC AEROSPACE]
              I dont think you can use nicchrome wire. check out Midwestern Tungsten s orphin bin or go to JK Leskers and look at all the stuff they have. The catalog is a
              Message 6 of 21 , Jul 3, 2008
                I dont think you can use nicchrome wire.  check out Midwestern Tungsten's orphin bin or go to JK Leskers and look at all the stuff they have.  The catalog is a serious source of info. 
                 
                Your welder is going to try to put out around 2kva.  Is your variac rated for 4kva ???  It better be or it will simply smoke.  Variac do not like max amp draw for very long......... they get hot and the insulation on the winding breaksdown.  
                 
                 


                From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On Behalf Of radroy92
                Sent: Wednesday, July 02, 2008 4:18 PM
                To: VacuumX@yahoogroups.com
                Subject: [VacuumX] Re: "Yellow Box Coater"

                Hi Andrew,

                The welder I want to use is a little Sears carbon arc/stick welder
                with a max output of 50 Amps at 45 volts or so. It runs on 120 Volts
                so I just plugged it into a 10 Amp Variac.

                Can Nichrome wire be used for emitters??

                Roy M.

                --- In VacuumX@yahoogroups .com, "Aurigema, Andrew N. (KSC)[ASRC
                AEROSPACE]" <andrew.n.aurigema@ ...> wrote:

                >
                > That is what is going
                to take you a lot of time to figure out. You
                can
                > use a lot of
                emmitters ( 18 or so ) close up ( a few inches
                away ) or
                > a lesser
                number farther back. In theory you could put one at the
                focal
                > point
                of the mirror and it would give you the best overall
                coating. But
                >
                you will need a long chamber with very very good vacuum for that.
                >
                > Not sure how you are using a variac and welder at the same time.
                >
                > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts
                stepdown
                > transformer. the 24 vac is just right to power 4 tungstens in
                series.
                > It took me a lot of experimentation to get the right number
                of
                emmitters
                > in series and parallel for my power supplies. Now I can
                start out
                > cherry red to wick the aluminum onto the tungsten then go to
                near
                white
                > hot for a few seconds then back to cherry and then off.
                If you hit
                the
                > power to fast the aluminum just melts and falls. that
                is very very
                very
                > bad for you mirror so dont ever let that happen.
                >
                > Andrew
                >
                >
                ____________ _________ _________ __
                >
                > From:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com [mailto:VacuumX@yahoogroups .com] On
                Behalf
                > Of radroy92
                > Sent: Tuesday, July 01, 2008 5:36
                PM
                > To:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com
                >
                Subject: [VacuumX] Re: "Yellow Box Coater"
                >
                >
                >
                >
                How many emitters would I need for a 12.5 mirror??
                >
                > I checked
                my litle welder I'm planning on using for a supply for
                the
                >
                emmitters. My Variac was putting out 13 Amps at 120 Volts. The
                > welder
                was putting out 30 Amps at 30 Volts. This was with a 3.5 "
                > long coil of
                3/32 stainless wire that measured 1.1 ohm. It was
                > glowing yellow hot
                laying on the concrete. Any more and it would
                > melt. It fused to the
                concrete and a few spots.
                >
                > Roy M.
                >
                > --- In
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com> ,
                > "Aurigema, Andrew
                N. (KSC)[ASRC
                > AEROSPACE]" <andrew.n.aurigema@ >
                wrote:
                > >
                > > You can use single wire emmitters. James does.
                his emmitters are
                > about
                > > 1mm diameter bent into a U shape.
                I bought the tri-wire ones that
                > are
                > > pre twisted so i could
                put more aluminum on each strand. I only
                > have 24
                > > emmitters
                and have to cover a 60" diameter disk so I needed to
                put
                >
                out
                > > some serious material. You cant put to much aluminunm on each
                wire
                > or
                > > the tungston disolves into the aluminum and
                you eat up the wires.
                > So I
                > > put 3 wires on each emmitter
                with three little strips of aluminum
                (
                > > about 60 mg total ) and
                zap it with lots of current.
                > >
                > > Andrew
                > >
                > > ____________ _________ _________ __
                > >
                > > From:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                > [mailto:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX%
                40yahoogroups. com> ] On
                > Behalf
                > > Of radroy92
                > > Sent: Tuesday, July 01, 2008 2:07 PM
                > >
                To: VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                > > Subject:
                [VacuumX] Re: "Yellow Box Coater"
                > >
                > >
                > >
                > > Why do we have to use heavy emmitters like that can we use
                thinner
                > > wire? Or does it fall apart at those
                temperatures?
                > >
                > > Roy M.
                > >
                > > ---
                In VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                >
                <mailto:VacuumX% 40yahoogroups. com> ,
                > > "Aurigema,
                Andrew N. (KSC)[ASRC
                > > AEROSPACE]" <andrew.n.aurigema@ >
                wrote:
                > > >
                > > > Get a big variac for that. I burned
                up a 1kw unit discovering
                > that
                > > they
                > > > are
                not rated to what they say they can take. go twice what you
                > >
                think
                > > > you need. You know you need a serious stepdown
                transformer to
                make
                > > > lots of amps at low voltage ( like 30
                amps at 3 vac for each
                > > emmitter ).
                > > >
                > > >
                > > > I just chatted with James a few minutes ago so I know he
                is at
                > least
                > > > typing. He may not be monitoring this
                list right now.
                > > >
                > > > Andrew in sunny
                FLA
                > > >
                > > >
                > > >
                > > >
                ____________ _________ _________ __
                > > >
                > > > From:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                >
                <mailto:VacuumX% 40yahoogroups. com>
                > > [mailto:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                >
                <mailto:VacuumX%
                > 40yahoogroups. com> ] On
                > >
                Behalf
                > > > Of radroy92
                > > > Sent: Monday, June 30,
                2008 12:53 PM
                > > > To:
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX% 40yahoogroups. com>
                >
                <mailto:VacuumX% 40yahoogroups. com>
                > > > Subject:
                [VacuumX] Re: "Yellow Box Coater"
                > > >
                > > >
                > > >
                > > > --- In
                href="mailto:VacuumX%40yahoogroups.com">VacuumX@yahoogroups .com <mailto:VacuumX%
                40yahoogroups. com>
                >
                <mailto:VacuumX% 40yahoogroups. com>
                > >
                <mailto:VacuumX% 40yahoogroups. com> ,
                > > >
                "glinos7124" <tg@> wrote:
                > > > >
                > > > >
                > > > > Does anyone have any details on the Lerch/Jones box
                coater
                > > > > at the St. Petersburg Mirror Lab?
                > > > >
                > > > > Dimensions, materials, pumps, sensors,....
                that kind of thing.
                > > > >
                > > > > I'm mulling
                over building one.
                > > > > It looks like a challenging, but
                doable project.
                > > > >
                > > > > tom
                > > > >
                > > >
                > > > By they way I'm working on a
                similar project. I have almost
                > > everything
                > > > and
                I'm hooking up power for my new TIG welder so I can
                assemble
                > >
                some
                > > > of the parts. I have purchased most of the parts from
                eBay and
                > the
                > > rest
                > > > came from the local
                Menards, a surplus metal supplier and some
                > > dumpster
                > > > diving. I'm currently on the tail end of cleaning my ancient
                NRC
                > 4"
                > > > diff. pump. Looks like somebody let it overheat
                and part of the
                > > > aluminum splash shield was fused to the
                bottom of the pump. For
                > my
                > > > initial chamber I have
                sectioned a 12" compressor tank and
                > > purchased an
                > > > angle flange from McMaster Carr to use in forming the sealing
                > >
                surface
                > > > at the open end. I have a small welder that I'm
                planning on
                using
                > > to
                > > > power the evap. coils
                and will controll it with a Variac.
                > > >
                > > > Roy
                M.
                > > >
                > >
                >

              • henry_3507
                I read that there are problems controlling highly inductive loads with a simple variac since they break. There is a reason for this: they are not meant to be
                Message 7 of 21 , Jul 14, 2008
                  I read that there are problems controlling highly inductive loads
                  with a simple variac since they break. There is a reason for this:
                  they are not meant to be used with inductive loads, only resistive
                  loads like lamps. The simple schematic that these variacs normally is
                  built around isnt constructed to be used with inductive loads and
                  could, depending on the load, be quickly destroyed. If a really heavy
                  duty variac is used so will it hold just because the triac in it is
                  bigger.


                  I have a big microwaveoven transformer rated 2750W that i have
                  rewound the secondary on. After that so did i get 5.4V and 1036A with
                  shorted secondary but i needed to be able to control the output so i
                  could control the temperature on the coils. I have now build a triac-
                  based controller for highly inductive loads like an transformer are
                  and i can now regulate the output power and the heat of the coil
                  without any step from 0 to 100%. Thanks to that its meant to handle
                  highly inductive loads so is a small 6A enough and its hardly gets
                  warm with an output of 100A from the transformer.




                  --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
                  AEROSPACE]" <andrew.n.aurigema@...> wrote:
                  >
                  > I dont think you can use nicchrome wire. check out Midwestern
                  > Tungsten's orphin bin or go to JK Leskers and look at all the stuff
                  they
                  > have. The catalog is a serious source of info.
                  >
                  > Your welder is going to try to put out around 2kva. Is your variac
                  > rated for 4kva ??? It better be or it will simply smoke. Variac
                  do not
                  > like max amp draw for very long......... they get hot and the
                  insulation
                  > on the winding breaksdown.
                  >
                  >
                  >
                  > ________________________________
                  >
                  > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On
                  Behalf
                  > Of radroy92
                  > Sent: Wednesday, July 02, 2008 4:18 PM
                  > To: VacuumX@yahoogroups.com
                  > Subject: [VacuumX] Re: "Yellow Box Coater"
                  >
                  >
                  >
                  > Hi Andrew,
                  >
                  > The welder I want to use is a little Sears carbon arc/stick welder
                  > with a max output of 50 Amps at 45 volts or so. It runs on 120
                  Volts
                  > so I just plugged it into a 10 Amp Variac.
                  >
                  > Can Nichrome wire be used for emitters??
                  >
                  > Roy M.
                  >
                  > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com> ,
                  > "Aurigema, Andrew N. (KSC)[ASRC
                  > AEROSPACE]" <andrew.n.aurigema@> wrote:
                  > >
                  > > That is what is going to take you a lot of time to figure out.
                  You
                  > can
                  > > use a lot of emmitters ( 18 or so ) close up ( a few inches
                  > away ) or
                  > > a lesser number farther back. In theory you could put one at the
                  > focal
                  > > point of the mirror and it would give you the best overall
                  > coating. But
                  > > you will need a long chamber with very very good vacuum for that.
                  > >
                  > > Not sure how you are using a variac and welder at the same time.
                  > >
                  > > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts
                  stepdown
                  > > transformer. the 24 vac is just right to power 4 tungstens in
                  > series.
                  > > It took me a lot of experimentation to get the right number of
                  > emmitters
                  > > in series and parallel for my power supplies. Now I can start out
                  > > cherry red to wick the aluminum onto the tungsten then go to near
                  > white
                  > > hot for a few seconds then back to cherry and then off. If you
                  hit
                  > the
                  > > power to fast the aluminum just melts and falls. that is very
                  very
                  > very
                  > > bad for you mirror so dont ever let that happen.
                  > >
                  > > Andrew
                  > >
                  > > ________________________________
                  > >
                  > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                  40yahoogroups.com> ] On
                  > Behalf
                  > > Of radroy92
                  > > Sent: Tuesday, July 01, 2008 5:36 PM
                  > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > > Subject: [VacuumX] Re: "Yellow Box Coater"
                  > >
                  > >
                  > >
                  > > How many emitters would I need for a 12.5 mirror??
                  > >
                  > > I checked my litle welder I'm planning on using for a supply for
                  > the
                  > > emmitters. My Variac was putting out 13 Amps at 120 Volts. The
                  > > welder was putting out 30 Amps at 30 Volts. This was with a 3.5 "
                  > > long coil of 3/32 stainless wire that measured 1.1 ohm. It was
                  > > glowing yellow hot laying on the concrete. Any more and it would
                  > > melt. It fused to the concrete and a few spots.
                  > >
                  > > Roy M.
                  > >
                  > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com> ,
                  > > "Aurigema, Andrew N. (KSC)[ASRC
                  > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                  > > >
                  > > > You can use single wire emmitters. James does. his emmitters
                  are
                  > > about
                  > > > 1mm diameter bent into a U shape. I bought the tri-wire ones
                  that
                  > > are
                  > > > pre twisted so i could put more aluminum on each strand. I only
                  > > have 24
                  > > > emmitters and have to cover a 60" diameter disk so I needed to
                  > put
                  > > out
                  > > > some serious material. You cant put to much aluminunm on each
                  > wire
                  > > or
                  > > > the tungston disolves into the aluminum and you eat up the
                  wires.
                  > > So I
                  > > > put 3 wires on each emmitter with three little strips of
                  aluminum
                  > (
                  > > > about 60 mg total ) and zap it with lots of current.
                  > > >
                  > > > Andrew
                  > > >
                  > > > ________________________________
                  > > >
                  > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > <mailto:VacuumX%
                  > 40yahoogroups.com> ] On
                  > > Behalf
                  > > > Of radroy92
                  > > > Sent: Tuesday, July 01, 2008 2:07 PM
                  > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                  > > >
                  > > >
                  > > >
                  > > > Why do we have to use heavy emmitters like that can we use
                  > thinner
                  > > > wire? Or does it fall apart at those temperatures?
                  > > >
                  > > > Roy M.
                  > > >
                  > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                  40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > <mailto:VacuumX%40yahoogroups.com> ,
                  > > > "Aurigema, Andrew N. (KSC)[ASRC
                  > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                  > > > >
                  > > > > Get a big variac for that. I burned up a 1kw unit discovering
                  > > that
                  > > > they
                  > > > > are not rated to what they say they can take. go twice what
                  you
                  > > > think
                  > > > > you need. You know you need a serious stepdown transformer to
                  > make
                  > > > > lots of amps at low voltage ( like 30 amps at 3 vac for each
                  > > > emmitter ).
                  > > > >
                  > > > >
                  > > > > I just chatted with James a few minutes ago so I know he is
                  at
                  > > least
                  > > > > typing. He may not be monitoring this list right now.
                  > > > >
                  > > > > Andrew in sunny FLA
                  > > > >
                  > > > >
                  > > > >
                  > > > > ________________________________
                  > > > >
                  > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                  40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > <mailto:VacuumX%40yahoogroups.com>
                  > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                  40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > <mailto:VacuumX%
                  > > 40yahoogroups.com> ] On
                  > > > Behalf
                  > > > > Of radroy92
                  > > > > Sent: Monday, June 30, 2008 12:53 PM
                  > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                  > <mailto:VacuumX%40yahoogroups.com>
                  > > <mailto:VacuumX%40yahoogroups.com>
                  > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                  > > > >
                  > > > >
                  > > > >
                  > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                  40yahoogroups.com>
                  > <mailto:VacuumX%
                  > 40yahoogroups.com>
                  > > <mailto:VacuumX%40yahoogroups.com>
                  > > > <mailto:VacuumX%40yahoogroups.com> ,
                  > > > > "glinos7124" <tg@> wrote:
                  > > > > >
                  > > > > >
                  > > > > > Does anyone have any details on the Lerch/Jones box coater
                  > > > > > at the St. Petersburg Mirror Lab?
                  > > > > >
                  > > > > > Dimensions, materials, pumps, sensors,.... that kind of
                  thing.
                  > > > > >
                  > > > > > I'm mulling over building one.
                  > > > > > It looks like a challenging, but doable project.
                  > > > > >
                  > > > > > tom
                  > > > > >
                  > > > >
                  > > > > By they way I'm working on a similar project. I have almost
                  > > > everything
                  > > > > and I'm hooking up power for my new TIG welder so I can
                  > assemble
                  > > > some
                  > > > > of the parts. I have purchased most of the parts from eBay
                  and
                  > > the
                  > > > rest
                  > > > > came from the local Menards, a surplus metal supplier and
                  some
                  > > > dumpster
                  > > > > diving. I'm currently on the tail end of cleaning my ancient
                  > NRC
                  > > 4"
                  > > > > diff. pump. Looks like somebody let it overheat and part of
                  the
                  > > > > aluminum splash shield was fused to the bottom of the pump.
                  For
                  > > my
                  > > > > initial chamber I have sectioned a 12" compressor tank and
                  > > > purchased an
                  > > > > angle flange from McMaster Carr to use in forming the sealing
                  > > > surface
                  > > > > at the open end. I have a small welder that I'm planning on
                  > using
                  > > > to
                  > > > > power the evap. coils and will controll it with a Variac.
                  > > > >
                  > > > > Roy M.
                  > > > >
                  > > >
                  > >
                  >
                • jacques savard
                  they are inductive controler out there it is for vacuum fan in kitchen a bit inductive load but the load you have is very special at the beginning it is very
                  Message 8 of 21 , Jul 14, 2008
                    they are inductive controler out there

                    it is for vacuum fan in kitchen a bit inductive load

                    but the load you have is very special
                    at the beginning it is very loo resistor when the heat come the resistor
                    increase and if the element cut no load
                    this give you variation in load or spicke that is very difficult for
                    inductive load
                    and if you used only 100 amp on decondary try to have a tranformer whit a
                    max capacity of 150 not 1030A
                    you are in the lower part of the operating rage

                    jack 47'N 71'W


                    > I read that there are problems controlling highly inductive loads
                    > with a simple variac since they break. There is a reason for this:
                    > they are not meant to be used with inductive loads, only resistive
                    > loads like lamps. The simple schematic that these variacs normally is
                    > built around isnt constructed to be used with inductive loads and
                    > could, depending on the load, be quickly destroyed. If a really heavy
                    > duty variac is used so will it hold just because the triac in it is
                    > bigger.
                    >
                    >
                    > I have a big microwaveoven transformer rated 2750W that i have
                    > rewound the secondary on. After that so did i get 5.4V and 1036A with
                    > shorted secondary but i needed to be able to control the output so i
                    > could control the temperature on the coils. I have now build a triac-
                    > based controller for highly inductive loads like an transformer are
                    > and i can now regulate the output power and the heat of the coil
                    > without any step from 0 to 100%. Thanks to that its meant to handle
                    > highly inductive loads so is a small 6A enough and its hardly gets
                    > warm with an output of 100A from the transformer.
                    >
                    >
                    >
                    >
                    > --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
                    > AEROSPACE]" <andrew.n.aurigema@...> wrote:
                    > >
                    > > I dont think you can use nicchrome wire. check out Midwestern
                    > > Tungsten's orphin bin or go to JK Leskers and look at all the stuff
                    > they
                    > > have. The catalog is a serious source of info.
                    > >
                    > > Your welder is going to try to put out around 2kva. Is your variac
                    > > rated for 4kva ??? It better be or it will simply smoke. Variac
                    > do not
                    > > like max amp draw for very long......... they get hot and the
                    > insulation
                    > > on the winding breaksdown.
                    > >
                    > >
                    > >
                    > > ________________________________
                    > >
                    > > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com] On
                    > Behalf
                    > > Of radroy92
                    > > Sent: Wednesday, July 02, 2008 4:18 PM
                    > > To: VacuumX@yahoogroups.com
                    > > Subject: [VacuumX] Re: "Yellow Box Coater"
                    > >
                    > >
                    > >
                    > > Hi Andrew,
                    > >
                    > > The welder I want to use is a little Sears carbon arc/stick welder
                    > > with a max output of 50 Amps at 45 volts or so. It runs on 120
                    > Volts
                    > > so I just plugged it into a 10 Amp Variac.
                    > >
                    > > Can Nichrome wire be used for emitters??
                    > >
                    > > Roy M.
                    > >
                    > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com> ,
                    > > "Aurigema, Andrew N. (KSC)[ASRC
                    > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                    > > >
                    > > > That is what is going to take you a lot of time to figure out.
                    > You
                    > > can
                    > > > use a lot of emmitters ( 18 or so ) close up ( a few inches
                    > > away ) or
                    > > > a lesser number farther back. In theory you could put one at the
                    > > focal
                    > > > point of the mirror and it would give you the best overall
                    > > coating. But
                    > > > you will need a long chamber with very very good vacuum for that.
                    > > >
                    > > > Not sure how you are using a variac and welder at the same time.
                    > > >
                    > > > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts
                    > stepdown
                    > > > transformer. the 24 vac is just right to power 4 tungstens in
                    > > series.
                    > > > It took me a lot of experimentation to get the right number of
                    > > emmitters
                    > > > in series and parallel for my power supplies. Now I can start out
                    > > > cherry red to wick the aluminum onto the tungsten then go to near
                    > > white
                    > > > hot for a few seconds then back to cherry and then off. If you
                    > hit
                    > > the
                    > > > power to fast the aluminum just melts and falls. that is very
                    > very
                    > > very
                    > > > bad for you mirror so dont ever let that happen.
                    > > >
                    > > > Andrew
                    > > >
                    > > > ________________________________
                    > > >
                    > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                    > 40yahoogroups.com> ] On
                    > > Behalf
                    > > > Of radroy92
                    > > > Sent: Tuesday, July 01, 2008 5:36 PM
                    > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                    > > >
                    > > >
                    > > >
                    > > > How many emitters would I need for a 12.5 mirror??
                    > > >
                    > > > I checked my litle welder I'm planning on using for a supply for
                    > > the
                    > > > emmitters. My Variac was putting out 13 Amps at 120 Volts. The
                    > > > welder was putting out 30 Amps at 30 Volts. This was with a 3.5 "
                    > > > long coil of 3/32 stainless wire that measured 1.1 ohm. It was
                    > > > glowing yellow hot laying on the concrete. Any more and it would
                    > > > melt. It fused to the concrete and a few spots.
                    > > >
                    > > > Roy M.
                    > > >
                    > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com> ,
                    > > > "Aurigema, Andrew N. (KSC)[ASRC
                    > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                    > > > >
                    > > > > You can use single wire emmitters. James does. his emmitters
                    > are
                    > > > about
                    > > > > 1mm diameter bent into a U shape. I bought the tri-wire ones
                    > that
                    > > > are
                    > > > > pre twisted so i could put more aluminum on each strand. I only
                    > > > have 24
                    > > > > emmitters and have to cover a 60" diameter disk so I needed to
                    > > put
                    > > > out
                    > > > > some serious material. You cant put to much aluminunm on each
                    > > wire
                    > > > or
                    > > > > the tungston disolves into the aluminum and you eat up the
                    > wires.
                    > > > So I
                    > > > > put 3 wires on each emmitter with three little strips of
                    > aluminum
                    > > (
                    > > > > about 60 mg total ) and zap it with lots of current.
                    > > > >
                    > > > > Andrew
                    > > > >
                    > > > > ________________________________
                    > > > >
                    > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > <mailto:VacuumX%
                    > > 40yahoogroups.com> ] On
                    > > > Behalf
                    > > > > Of radroy92
                    > > > > Sent: Tuesday, July 01, 2008 2:07 PM
                    > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                    > > > >
                    > > > >
                    > > > >
                    > > > > Why do we have to use heavy emmitters like that can we use
                    > > thinner
                    > > > > wire? Or does it fall apart at those temperatures?
                    > > > >
                    > > > > Roy M.
                    > > > >
                    > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                    > 40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > <mailto:VacuumX%40yahoogroups.com> ,
                    > > > > "Aurigema, Andrew N. (KSC)[ASRC
                    > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                    > > > > >
                    > > > > > Get a big variac for that. I burned up a 1kw unit discovering
                    > > > that
                    > > > > they
                    > > > > > are not rated to what they say they can take. go twice what
                    > you
                    > > > > think
                    > > > > > you need. You know you need a serious stepdown transformer to
                    > > make
                    > > > > > lots of amps at low voltage ( like 30 amps at 3 vac for each
                    > > > > emmitter ).
                    > > > > >
                    > > > > >
                    > > > > > I just chatted with James a few minutes ago so I know he is
                    > at
                    > > > least
                    > > > > > typing. He may not be monitoring this list right now.
                    > > > > >
                    > > > > > Andrew in sunny FLA
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > ________________________________
                    > > > > >
                    > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                    > 40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > <mailto:VacuumX%40yahoogroups.com>
                    > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                    > 40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > <mailto:VacuumX%
                    > > > 40yahoogroups.com> ] On
                    > > > > Behalf
                    > > > > > Of radroy92
                    > > > > > Sent: Monday, June 30, 2008 12:53 PM
                    > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                    > > <mailto:VacuumX%40yahoogroups.com>
                    > > > <mailto:VacuumX%40yahoogroups.com>
                    > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                    > > > > >
                    > > > > >
                    > > > > >
                    > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                    > 40yahoogroups.com>
                    > > <mailto:VacuumX%
                    > > 40yahoogroups.com>
                    > > > <mailto:VacuumX%40yahoogroups.com>
                    > > > > <mailto:VacuumX%40yahoogroups.com> ,
                    > > > > > "glinos7124" <tg@> wrote:
                    > > > > > >
                    > > > > > >
                    > > > > > > Does anyone have any details on the Lerch/Jones box coater
                    > > > > > > at the St. Petersburg Mirror Lab?
                    > > > > > >
                    > > > > > > Dimensions, materials, pumps, sensors,.... that kind of
                    > thing.
                    > > > > > >
                    > > > > > > I'm mulling over building one.
                    > > > > > > It looks like a challenging, but doable project.
                    > > > > > >
                    > > > > > > tom
                    > > > > > >
                    > > > > >
                    > > > > > By they way I'm working on a similar project. I have almost
                    > > > > everything
                    > > > > > and I'm hooking up power for my new TIG welder so I can
                    > > assemble
                    > > > > some
                    > > > > > of the parts. I have purchased most of the parts from eBay
                    > and
                    > > > the
                    > > > > rest
                    > > > > > came from the local Menards, a surplus metal supplier and
                    > some
                    > > > > dumpster
                    > > > > > diving. I'm currently on the tail end of cleaning my ancient
                    > > NRC
                    > > > 4"
                    > > > > > diff. pump. Looks like somebody let it overheat and part of
                    > the
                    > > > > > aluminum splash shield was fused to the bottom of the pump.
                    > For
                    > > > my
                    > > > > > initial chamber I have sectioned a 12" compressor tank and
                    > > > > purchased an
                    > > > > > angle flange from McMaster Carr to use in forming the sealing
                    > > > > surface
                    > > > > > at the open end. I have a small welder that I'm planning on
                    > > using
                    > > > > to
                    > > > > > power the evap. coils and will controll it with a Variac.
                    > > > > >
                    > > > > > Roy M.
                    > > > > >
                    > > > >
                    > > >
                    > >
                    >
                    >
                    >
                    > ------------------------------------
                    >
                    > Yahoo! Groups Links
                    >
                    >
                    >
                  • henry_3507
                    The 100A was just an example, and the 1036A is when the secondary is shorted and that would be over 5000W but that was just to say how much it can put out
                    Message 9 of 21 , Jul 14, 2008
                      The 100A was just an example, and the 1036A is when the secondary is
                      shorted and that would be over 5000W but that was just to say how
                      much it can put out during a very few seconds nothing else. I will
                      use more or less the entire capacity of the transformer later on but
                      max would be 2300W because the fuse here is 10A and we use 230V so
                      max is 2300W on the output which would be 425A as max with 5.4V which
                      would be enough.

                      Normally would i use everything between 160 - 425A so it need to be
                      this big. But the transformer and the controling circuit i built
                      works just fine even at only a few watts output with no problems at
                      all and i have checked it in a oscilloscope and it works perfect no
                      matter the output.

                      Kitchen fans are not near as inductive as a big transformer so they
                      could be controlled with a more or less ordinary variac schematic.

                      --- In VacuumX@yahoogroups.com, jacques savard <jacquessavard@...>
                      wrote:
                      >
                      >
                      > they are inductive controler out there
                      >
                      > it is for vacuum fan in kitchen a bit inductive load
                      >
                      > but the load you have is very special
                      > at the beginning it is very loo resistor when the heat come the
                      resistor
                      > increase and if the element cut no load
                      > this give you variation in load or spicke that is very difficult for
                      > inductive load
                      > and if you used only 100 amp on decondary try to have a tranformer
                      whit a
                      > max capacity of 150 not 1030A
                      > you are in the lower part of the operating rage
                      >
                      > jack 47'N 71'W
                      >
                      >
                      > > I read that there are problems controlling highly inductive loads
                      > > with a simple variac since they break. There is a reason for this:
                      > > they are not meant to be used with inductive loads, only resistive
                      > > loads like lamps. The simple schematic that these variacs
                      normally is
                      > > built around isnt constructed to be used with inductive loads and
                      > > could, depending on the load, be quickly destroyed. If a really
                      heavy
                      > > duty variac is used so will it hold just because the triac in it
                      is
                      > > bigger.
                      > >
                      > >
                      > > I have a big microwaveoven transformer rated 2750W that i have
                      > > rewound the secondary on. After that so did i get 5.4V and 1036A
                      with
                      > > shorted secondary but i needed to be able to control the output
                      so i
                      > > could control the temperature on the coils. I have now build a
                      triac-
                      > > based controller for highly inductive loads like an transformer
                      are
                      > > and i can now regulate the output power and the heat of the coil
                      > > without any step from 0 to 100%. Thanks to that its meant to
                      handle
                      > > highly inductive loads so is a small 6A enough and its hardly gets
                      > > warm with an output of 100A from the transformer.
                      > >
                      > >
                      > >
                      > >
                      > > --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
                      > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                      > > >
                      > > > I dont think you can use nicchrome wire. check out Midwestern
                      > > > Tungsten's orphin bin or go to JK Leskers and look at all the
                      stuff
                      > > they
                      > > > have. The catalog is a serious source of info.
                      > > >
                      > > > Your welder is going to try to put out around 2kva. Is your
                      variac
                      > > > rated for 4kva ??? It better be or it will simply smoke.
                      Variac
                      > > do not
                      > > > like max amp draw for very long......... they get hot and the
                      > > insulation
                      > > > on the winding breaksdown.
                      > > >
                      > > >
                      > > >
                      > > > ________________________________
                      > > >
                      > > > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com]
                      On
                      > > Behalf
                      > > > Of radroy92
                      > > > Sent: Wednesday, July 02, 2008 4:18 PM
                      > > > To: VacuumX@yahoogroups.com
                      > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                      > > >
                      > > >
                      > > >
                      > > > Hi Andrew,
                      > > >
                      > > > The welder I want to use is a little Sears carbon arc/stick
                      welder
                      > > > with a max output of 50 Amps at 45 volts or so. It runs on 120
                      > > Volts
                      > > > so I just plugged it into a 10 Amp Variac.
                      > > >
                      > > > Can Nichrome wire be used for emitters??
                      > > >
                      > > > Roy M.
                      > > >
                      > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com> ,
                      > > > "Aurigema, Andrew N. (KSC)[ASRC
                      > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                      > > > >
                      > > > > That is what is going to take you a lot of time to figure out.
                      > > You
                      > > > can
                      > > > > use a lot of emmitters ( 18 or so ) close up ( a few inches
                      > > > away ) or
                      > > > > a lesser number farther back. In theory you could put one at
                      the
                      > > > focal
                      > > > > point of the mirror and it would give you the best overall
                      > > > coating. But
                      > > > > you will need a long chamber with very very good vacuum for
                      that.
                      > > > >
                      > > > > Not sure how you are using a variac and welder at the same
                      time.
                      > > > >
                      > > > > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts
                      > > stepdown
                      > > > > transformer. the 24 vac is just right to power 4 tungstens in
                      > > > series.
                      > > > > It took me a lot of experimentation to get the right number of
                      > > > emmitters
                      > > > > in series and parallel for my power supplies. Now I can start
                      out
                      > > > > cherry red to wick the aluminum onto the tungsten then go to
                      near
                      > > > white
                      > > > > hot for a few seconds then back to cherry and then off. If you
                      > > hit
                      > > > the
                      > > > > power to fast the aluminum just melts and falls. that is very
                      > > very
                      > > > very
                      > > > > bad for you mirror so dont ever let that happen.
                      > > > >
                      > > > > Andrew
                      > > > >
                      > > > > ________________________________
                      > > > >
                      > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                      > > 40yahoogroups.com> ] On
                      > > > Behalf
                      > > > > Of radroy92
                      > > > > Sent: Tuesday, July 01, 2008 5:36 PM
                      > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                      > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                      > > > >
                      > > > >
                      > > > >
                      > > > > How many emitters would I need for a 12.5 mirror??
                      > > > >
                      > > > > I checked my litle welder I'm planning on using for a supply
                      for
                      > > > the
                      > > > > emmitters. My Variac was putting out 13 Amps at 120 Volts. The
                      > > > > welder was putting out 30 Amps at 30 Volts. This was with a
                      3.5 "
                      > > > > long coil of 3/32 stainless wire that measured 1.1 ohm. It was
                      > > > > glowing yellow hot laying on the concrete. Any more and it
                      would
                      > > > > melt. It fused to the concrete and a few spots.
                      > > > >
                      > > > > Roy M.
                      > > > >
                      > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com> ,
                      > > > > "Aurigema, Andrew N. (KSC)[ASRC
                      > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                      > > > > >
                      > > > > > You can use single wire emmitters. James does. his emmitters
                      > > are
                      > > > > about
                      > > > > > 1mm diameter bent into a U shape. I bought the tri-wire ones
                      > > that
                      > > > > are
                      > > > > > pre twisted so i could put more aluminum on each strand. I
                      only
                      > > > > have 24
                      > > > > > emmitters and have to cover a 60" diameter disk so I needed
                      to
                      > > > put
                      > > > > out
                      > > > > > some serious material. You cant put to much aluminunm on
                      each
                      > > > wire
                      > > > > or
                      > > > > > the tungston disolves into the aluminum and you eat up the
                      > > wires.
                      > > > > So I
                      > > > > > put 3 wires on each emmitter with three little strips of
                      > > aluminum
                      > > > (
                      > > > > > about 60 mg total ) and zap it with lots of current.
                      > > > > >
                      > > > > > Andrew
                      > > > > >
                      > > > > > ________________________________
                      > > > > >
                      > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > <mailto:VacuumX%
                      > > > 40yahoogroups.com> ] On
                      > > > > Behalf
                      > > > > > Of radroy92
                      > > > > > Sent: Tuesday, July 01, 2008 2:07 PM
                      > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                      > > > > >
                      > > > > >
                      > > > > >
                      > > > > > Why do we have to use heavy emmitters like that can we use
                      > > > thinner
                      > > > > > wire? Or does it fall apart at those temperatures?
                      > > > > >
                      > > > > > Roy M.
                      > > > > >
                      > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                      > > 40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > <mailto:VacuumX%40yahoogroups.com> ,
                      > > > > > "Aurigema, Andrew N. (KSC)[ASRC
                      > > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                      > > > > > >
                      > > > > > > Get a big variac for that. I burned up a 1kw unit
                      discovering
                      > > > > that
                      > > > > > they
                      > > > > > > are not rated to what they say they can take. go twice
                      what
                      > > you
                      > > > > > think
                      > > > > > > you need. You know you need a serious stepdown
                      transformer to
                      > > > make
                      > > > > > > lots of amps at low voltage ( like 30 amps at 3 vac for
                      each
                      > > > > > emmitter ).
                      > > > > > >
                      > > > > > >
                      > > > > > > I just chatted with James a few minutes ago so I know he
                      is
                      > > at
                      > > > > least
                      > > > > > > typing. He may not be monitoring this list right now.
                      > > > > > >
                      > > > > > > Andrew in sunny FLA
                      > > > > > >
                      > > > > > >
                      > > > > > >
                      > > > > > > ________________________________
                      > > > > > >
                      > > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                      > > 40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                      > > 40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > <mailto:VacuumX%
                      > > > > 40yahoogroups.com> ] On
                      > > > > > Behalf
                      > > > > > > Of radroy92
                      > > > > > > Sent: Monday, June 30, 2008 12:53 PM
                      > > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%
                      40yahoogroups.com>
                      > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                      > > > > > >
                      > > > > > >
                      > > > > > >
                      > > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                      > > 40yahoogroups.com>
                      > > > <mailto:VacuumX%
                      > > > 40yahoogroups.com>
                      > > > > <mailto:VacuumX%40yahoogroups.com>
                      > > > > > <mailto:VacuumX%40yahoogroups.com> ,
                      > > > > > > "glinos7124" <tg@> wrote:
                      > > > > > > >
                      > > > > > > >
                      > > > > > > > Does anyone have any details on the Lerch/Jones box
                      coater
                      > > > > > > > at the St. Petersburg Mirror Lab?
                      > > > > > > >
                      > > > > > > > Dimensions, materials, pumps, sensors,.... that kind of
                      > > thing.
                      > > > > > > >
                      > > > > > > > I'm mulling over building one.
                      > > > > > > > It looks like a challenging, but doable project.
                      > > > > > > >
                      > > > > > > > tom
                      > > > > > > >
                      > > > > > >
                      > > > > > > By they way I'm working on a similar project. I have
                      almost
                      > > > > > everything
                      > > > > > > and I'm hooking up power for my new TIG welder so I can
                      > > > assemble
                      > > > > > some
                      > > > > > > of the parts. I have purchased most of the parts from eBay
                      > > and
                      > > > > the
                      > > > > > rest
                      > > > > > > came from the local Menards, a surplus metal supplier and
                      > > some
                      > > > > > dumpster
                      > > > > > > diving. I'm currently on the tail end of cleaning my
                      ancient
                      > > > NRC
                      > > > > 4"
                      > > > > > > diff. pump. Looks like somebody let it overheat and part
                      of
                      > > the
                      > > > > > > aluminum splash shield was fused to the bottom of the
                      pump.
                      > > For
                      > > > > my
                      > > > > > > initial chamber I have sectioned a 12" compressor tank and
                      > > > > > purchased an
                      > > > > > > angle flange from McMaster Carr to use in forming the
                      sealing
                      > > > > > surface
                      > > > > > > at the open end. I have a small welder that I'm planning
                      on
                      > > > using
                      > > > > > to
                      > > > > > > power the evap. coils and will controll it with a Variac.
                      > > > > > >
                      > > > > > > Roy M.
                      > > > > > >
                      > > > > >
                      > > > >
                      > > >
                      > >
                      > >
                      > >
                      > > ------------------------------------
                      > >
                      > > Yahoo! Groups Links
                      > >
                      > >
                      > >
                      >
                    • jacques savard
                      a variac transformer can do the job at 6 amp easely and very safely not problemo whit short or spike of current a bit more expensive it is a variable
                      Message 10 of 21 , Jul 14, 2008
                        a variac transformer can do the job at 6 amp easely and very safely not
                        problemo whit short or spike of current

                        a bit more expensive it is a variable transformer only

                        sometime the old way to do the thing is still good

                        jack 47'N 71'W

                        > The 100A was just an example, and the 1036A is when the secondary is
                        > shorted and that would be over 5000W but that was just to say how
                        > much it can put out during a very few seconds nothing else. I will
                        > use more or less the entire capacity of the transformer later on but
                        > max would be 2300W because the fuse here is 10A and we use 230V so
                        > max is 2300W on the output which would be 425A as max with 5.4V which
                        > would be enough.
                        >
                        > Normally would i use everything between 160 - 425A so it need to be
                        > this big. But the transformer and the controling circuit i built
                        > works just fine even at only a few watts output with no problems at
                        > all and i have checked it in a oscilloscope and it works perfect no
                        > matter the output.
                        >
                        > Kitchen fans are not near as inductive as a big transformer so they
                        > could be controlled with a more or less ordinary variac schematic.
                        >
                        > --- In VacuumX@yahoogroups.com, jacques savard <jacquessavard@...>
                        > wrote:
                        > >
                        > >
                        > > they are inductive controler out there
                        > >
                        > > it is for vacuum fan in kitchen a bit inductive load
                        > >
                        > > but the load you have is very special
                        > > at the beginning it is very loo resistor when the heat come the
                        > resistor
                        > > increase and if the element cut no load
                        > > this give you variation in load or spicke that is very difficult for
                        > > inductive load
                        > > and if you used only 100 amp on decondary try to have a tranformer
                        > whit a
                        > > max capacity of 150 not 1030A
                        > > you are in the lower part of the operating rage
                        > >
                        > > jack 47'N 71'W
                        > >
                        > >
                        > > > I read that there are problems controlling highly inductive loads
                        > > > with a simple variac since they break. There is a reason for this:
                        > > > they are not meant to be used with inductive loads, only resistive
                        > > > loads like lamps. The simple schematic that these variacs
                        > normally is
                        > > > built around isnt constructed to be used with inductive loads and
                        > > > could, depending on the load, be quickly destroyed. If a really
                        > heavy
                        > > > duty variac is used so will it hold just because the triac in it
                        > is
                        > > > bigger.
                        > > >
                        > > >
                        > > > I have a big microwaveoven transformer rated 2750W that i have
                        > > > rewound the secondary on. After that so did i get 5.4V and 1036A
                        > with
                        > > > shorted secondary but i needed to be able to control the output
                        > so i
                        > > > could control the temperature on the coils. I have now build a
                        > triac-
                        > > > based controller for highly inductive loads like an transformer
                        > are
                        > > > and i can now regulate the output power and the heat of the coil
                        > > > without any step from 0 to 100%. Thanks to that its meant to
                        > handle
                        > > > highly inductive loads so is a small 6A enough and its hardly gets
                        > > > warm with an output of 100A from the transformer.
                        > > >
                        > > >
                        > > >
                        > > >
                        > > > --- In VacuumX@yahoogroups.com, "Aurigema, Andrew N. (KSC)[ASRC
                        > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                        > > > >
                        > > > > I dont think you can use nicchrome wire. check out Midwestern
                        > > > > Tungsten's orphin bin or go to JK Leskers and look at all the
                        > stuff
                        > > > they
                        > > > > have. The catalog is a serious source of info.
                        > > > >
                        > > > > Your welder is going to try to put out around 2kva. Is your
                        > variac
                        > > > > rated for 4kva ??? It better be or it will simply smoke.
                        > Variac
                        > > > do not
                        > > > > like max amp draw for very long......... they get hot and the
                        > > > insulation
                        > > > > on the winding breaksdown.
                        > > > >
                        > > > >
                        > > > >
                        > > > > ________________________________
                        > > > >
                        > > > > From: VacuumX@yahoogroups.com [mailto:VacuumX@yahoogroups.com]
                        > On
                        > > > Behalf
                        > > > > Of radroy92
                        > > > > Sent: Wednesday, July 02, 2008 4:18 PM
                        > > > > To: VacuumX@yahoogroups.com
                        > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                        > > > >
                        > > > >
                        > > > >
                        > > > > Hi Andrew,
                        > > > >
                        > > > > The welder I want to use is a little Sears carbon arc/stick
                        > welder
                        > > > > with a max output of 50 Amps at 45 volts or so. It runs on 120
                        > > > Volts
                        > > > > so I just plugged it into a 10 Amp Variac.
                        > > > >
                        > > > > Can Nichrome wire be used for emitters??
                        > > > >
                        > > > > Roy M.
                        > > > >
                        > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com> ,
                        > > > > "Aurigema, Andrew N. (KSC)[ASRC
                        > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                        > > > > >
                        > > > > > That is what is going to take you a lot of time to figure out.
                        > > > You
                        > > > > can
                        > > > > > use a lot of emmitters ( 18 or so ) close up ( a few inches
                        > > > > away ) or
                        > > > > > a lesser number farther back. In theory you could put one at
                        > the
                        > > > > focal
                        > > > > > point of the mirror and it would give you the best overall
                        > > > > coating. But
                        > > > > > you will need a long chamber with very very good vacuum for
                        > that.
                        > > > > >
                        > > > > > Not sure how you are using a variac and welder at the same
                        > time.
                        > > > > >
                        > > > > > I use my 2.5kva variac to power a 120 : 24 vac x 1500 watts
                        > > > stepdown
                        > > > > > transformer. the 24 vac is just right to power 4 tungstens in
                        > > > > series.
                        > > > > > It took me a lot of experimentation to get the right number of
                        > > > > emmitters
                        > > > > > in series and parallel for my power supplies. Now I can start
                        > out
                        > > > > > cherry red to wick the aluminum onto the tungsten then go to
                        > near
                        > > > > white
                        > > > > > hot for a few seconds then back to cherry and then off. If you
                        > > > hit
                        > > > > the
                        > > > > > power to fast the aluminum just melts and falls. that is very
                        > > > very
                        > > > > very
                        > > > > > bad for you mirror so dont ever let that happen.
                        > > > > >
                        > > > > > Andrew
                        > > > > >
                        > > > > > ________________________________
                        > > > > >
                        > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                        > > > 40yahoogroups.com> ] On
                        > > > > Behalf
                        > > > > > Of radroy92
                        > > > > > Sent: Tuesday, July 01, 2008 5:36 PM
                        > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%40yahoogroups.com>
                        > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                        > > > > >
                        > > > > >
                        > > > > >
                        > > > > > How many emitters would I need for a 12.5 mirror??
                        > > > > >
                        > > > > > I checked my litle welder I'm planning on using for a supply
                        > for
                        > > > > the
                        > > > > > emmitters. My Variac was putting out 13 Amps at 120 Volts. The
                        > > > > > welder was putting out 30 Amps at 30 Volts. This was with a
                        > 3.5 "
                        > > > > > long coil of 3/32 stainless wire that measured 1.1 ohm. It was
                        > > > > > glowing yellow hot laying on the concrete. Any more and it
                        > would
                        > > > > > melt. It fused to the concrete and a few spots.
                        > > > > >
                        > > > > > Roy M.
                        > > > > >
                        > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com> ,
                        > > > > > "Aurigema, Andrew N. (KSC)[ASRC
                        > > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                        > > > > > >
                        > > > > > > You can use single wire emmitters. James does. his emmitters
                        > > > are
                        > > > > > about
                        > > > > > > 1mm diameter bent into a U shape. I bought the tri-wire ones
                        > > > that
                        > > > > > are
                        > > > > > > pre twisted so i could put more aluminum on each strand. I
                        > only
                        > > > > > have 24
                        > > > > > > emmitters and have to cover a 60" diameter disk so I needed
                        > to
                        > > > > put
                        > > > > > out
                        > > > > > > some serious material. You cant put to much aluminunm on
                        > each
                        > > > > wire
                        > > > > > or
                        > > > > > > the tungston disolves into the aluminum and you eat up the
                        > > > wires.
                        > > > > > So I
                        > > > > > > put 3 wires on each emmitter with three little strips of
                        > > > aluminum
                        > > > > (
                        > > > > > > about 60 mg total ) and zap it with lots of current.
                        > > > > > >
                        > > > > > > Andrew
                        > > > > > >
                        > > > > > > ________________________________
                        > > > > > >
                        > > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%
                        > > > > 40yahoogroups.com> ] On
                        > > > > > Behalf
                        > > > > > > Of radroy92
                        > > > > > > Sent: Tuesday, July 01, 2008 2:07 PM
                        > > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                        > > > > > >
                        > > > > > >
                        > > > > > >
                        > > > > > > Why do we have to use heavy emmitters like that can we use
                        > > > > thinner
                        > > > > > > wire? Or does it fall apart at those temperatures?
                        > > > > > >
                        > > > > > > Roy M.
                        > > > > > >
                        > > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                        > > > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > <mailto:VacuumX%40yahoogroups.com> ,
                        > > > > > > "Aurigema, Andrew N. (KSC)[ASRC
                        > > > > > > AEROSPACE]" <andrew.n.aurigema@> wrote:
                        > > > > > > >
                        > > > > > > > Get a big variac for that. I burned up a 1kw unit
                        > discovering
                        > > > > > that
                        > > > > > > they
                        > > > > > > > are not rated to what they say they can take. go twice
                        > what
                        > > > you
                        > > > > > > think
                        > > > > > > > you need. You know you need a serious stepdown
                        > transformer to
                        > > > > make
                        > > > > > > > lots of amps at low voltage ( like 30 amps at 3 vac for
                        > each
                        > > > > > > emmitter ).
                        > > > > > > >
                        > > > > > > >
                        > > > > > > > I just chatted with James a few minutes ago so I know he
                        > is
                        > > > at
                        > > > > > least
                        > > > > > > > typing. He may not be monitoring this list right now.
                        > > > > > > >
                        > > > > > > > Andrew in sunny FLA
                        > > > > > > >
                        > > > > > > >
                        > > > > > > >
                        > > > > > > > ________________________________
                        > > > > > > >
                        > > > > > > > From: VacuumX@yahoogroups.com <mailto:VacuumX%
                        > > > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > > [mailto:VacuumX@yahoogroups.com <mailto:VacuumX%
                        > > > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > <mailto:VacuumX%
                        > > > > > 40yahoogroups.com> ] On
                        > > > > > > Behalf
                        > > > > > > > Of radroy92
                        > > > > > > > Sent: Monday, June 30, 2008 12:53 PM
                        > > > > > > > To: VacuumX@yahoogroups.com <mailto:VacuumX%
                        > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > > > Subject: [VacuumX] Re: "Yellow Box Coater"
                        > > > > > > >
                        > > > > > > >
                        > > > > > > >
                        > > > > > > > --- In VacuumX@yahoogroups.com <mailto:VacuumX%
                        > > > 40yahoogroups.com>
                        > > > > <mailto:VacuumX%
                        > > > > 40yahoogroups.com>
                        > > > > > <mailto:VacuumX%40yahoogroups.com>
                        > > > > > > <mailto:VacuumX%40yahoogroups.com> ,
                        > > > > > > > "glinos7124" <tg@> wrote:
                        > > > > > > > >
                        > > > > > > > >
                        > > > > > > > > Does anyone have any details on the Lerch/Jones box
                        > coater
                        > > > > > > > > at the St. Petersburg Mirror Lab?
                        > > > > > > > >
                        > > > > > > > > Dimensions, materials, pumps, sensors,.... that kind of
                        > > > thing.
                        > > > > > > > >
                        > > > > > > > > I'm mulling over building one.
                        > > > > > > > > It looks like a challenging, but doable project.
                        > > > > > > > >
                        > > > > > > > > tom
                        > > > > > > > >
                        > > > > > > >
                        > > > > > > > By they way I'm working on a similar project. I have
                        > almost
                        > > > > > > everything
                        > > > > > > > and I'm hooking up power for my new TIG welder so I can
                        > > > > assemble
                        > > > > > > some
                        > > > > > > > of the parts. I have purchased most of the parts from eBay
                        > > > and
                        > > > > > the
                        > > > > > > rest
                        > > > > > > > came from the local Menards, a surplus metal supplier and
                        > > > some
                        > > > > > > dumpster
                        > > > > > > > diving. I'm currently on the tail end of cleaning my
                        > ancient
                        > > > > NRC
                        > > > > > 4"
                        > > > > > > > diff. pump. Looks like somebody let it overheat and part
                        > of
                        > > > the
                        > > > > > > > aluminum splash shield was fused to the bottom of the
                        > pump.
                        > > > For
                        > > > > > my
                        > > > > > > > initial chamber I have sectioned a 12" compressor tank and
                        > > > > > > purchased an
                        > > > > > > > angle flange from McMaster Carr to use in forming the
                        > sealing
                        > > > > > > surface
                        > > > > > > > at the open end. I have a small welder that I'm planning
                        > on
                        > > > > using
                        > > > > > > to
                        > > > > > > > power the evap. coils and will controll it with a Variac.
                        > > > > > > >
                        > > > > > > > Roy M.
                        > > > > > > >
                        > > > > > >
                        > > > > >
                        > > > >
                        > > >
                        > > >
                        > > >
                        > > > ------------------------------------
                        > > >
                        > > > Yahoo! Groups Links
                        > > >
                        > > >
                        > > >
                        > >
                        >
                        >
                        >
                        > ------------------------------------
                        >
                        > Yahoo! Groups Links
                        >
                        >
                        >
                        >
                      • Gomez Addams
                        ... There s something I m missing here. 1. There is no triac in a variac. Variac is one of several trademarks for a variable transformer. Powerstat is
                        Message 11 of 21 , Jul 14, 2008
                          On Jul 14, 2008, at 11:23 AM, henry_3507 wrote:

                          > I read that there are problems controlling highly inductive loads
                          > with a simple variac since they break. There is a reason for this:
                          > they are not meant to be used with inductive loads, only resistive
                          > loads like lamps. The simple schematic that these variacs normally is
                          > built around isnt constructed to be used with inductive loads and
                          > could, depending on the load, be quickly destroyed. If a really heavy
                          > duty variac is used so will it hold just because the triac in it is
                          > bigger.

                          There's something I'm missing here.

                          1. There is no triac in a variac. "Variac" is one of several trademarks
                          for a variable transformer. "Powerstat" is another. A triac is a solid
                          state switching device. You would not normally find one in or even
                          associated with, a variable transformer.

                          2. Variable transformers are generally MUCH more robust and rugged than
                          solid state switching devices.

                          For decades, I and many other Tesla coil enthusiasts have been using
                          variable transformers to control one of the worst (from an electrical
                          standpoint) loads there is - disruptive discharge, spark gap type Tesla
                          coils. The load is intermittent, highly inductive (due to large high
                          voltage transformers) is intermittent due to the spark gap's firing,
                          and often puts spits large amounts of RFI and high voltage spikes back
                          toward the variac. Only recently (within the last ten years or so)
                          have Tesla coil enthusiasts started building solid state controls that
                          will handle a large (several kilowatts or more) Tesla coil without
                          breaking.

                          > I have a big microwaveoven transformer rated 2750W that i have
                          > rewound the secondary on. After that so did i get 5.4V and 1036A with
                          > shorted secondary but i needed to be able to control the output so i
                          > could control the temperature on the coils. I have now build a triac-
                          > based controller for highly inductive loads like an transformer are
                          > and i can now regulate the output power and the heat of the coil
                          > without any step from 0 to 100%. Thanks to that its meant to handle
                          > highly inductive loads so is a small 6A enough and its hardly gets
                          > warm with an output of 100A from the transformer.

                          One thing you will discover after you've worked with solid state
                          switching devices for a while, especially when you're doing phase
                          angle control of inductive loads, is that two SCRs connected back-to
                          -back are much more reliable, and handle surges and unexpected load
                          behavior much better than a triac. If you compare an SCR and a TRIAC
                          having identical PRV and I(f) ratings, you will find that the I(tsm)
                          for the SCR is typically much larger than the TRIAC's.

                          Greatly over-specifying the switching device is not the usual solution.
                          The usual (and cheaper) solution to nasty loads (provided they remain
                          generally within the safe operating area of the device) is to place a
                          snubber network (can be as simple as a capacitor and resistor in
                          series) across the device to limit the reverse voltage rise time
                          appearing on the device's terminals.

                          - Bill "Gomez" Lemieux
                        • henry_3507
                          Ok, there has been a real mixup here because in Sweden so is a triac based regulator often called a variac since they do about the same thing as a transformer
                          Message 12 of 21 , Jul 14, 2008
                            Ok, there has been a real mixup here because in Sweden so is a triac
                            based regulator often called a variac since they do about the same
                            thing as a transformer based depending on how you use it - control
                            the power. The transformer based is normally not called variac but
                            something else that describes exactly what it is.

                            The international name is variac but it is very rarely used for the
                            tranformer type here so i didnt got that it was the transformer based
                            type that was meant. But then it all makes sense since some things
                            just really didnt add up.

                            So then just ignore all i said before since i was talking about a
                            triac based control unit.




                            --- In VacuumX@yahoogroups.com, Gomez Addams <gomez@...> wrote:
                            >
                            >
                            > On Jul 14, 2008, at 11:23 AM, henry_3507 wrote:
                            >
                            > > I read that there are problems controlling highly inductive loads
                            > > with a simple variac since they break. There is a reason for this:
                            > > they are not meant to be used with inductive loads, only resistive
                            > > loads like lamps. The simple schematic that these variacs
                            normally is
                            > > built around isnt constructed to be used with inductive loads and
                            > > could, depending on the load, be quickly destroyed. If a really
                            heavy
                            > > duty variac is used so will it hold just because the triac in it
                            is
                            > > bigger.
                            >
                            > There's something I'm missing here.
                            >
                            > 1. There is no triac in a variac. "Variac" is one of several
                            trademarks
                            > for a variable transformer. "Powerstat" is another. A triac is a
                            solid
                            > state switching device. You would not normally find one in or even
                            > associated with, a variable transformer.
                            >
                            > 2. Variable transformers are generally MUCH more robust and rugged
                            than
                            > solid state switching devices.
                            >
                            > For decades, I and many other Tesla coil enthusiasts have been using
                            > variable transformers to control one of the worst (from an
                            electrical
                            > standpoint) loads there is - disruptive discharge, spark gap type
                            Tesla
                            > coils. The load is intermittent, highly inductive (due to large
                            high
                            > voltage transformers) is intermittent due to the spark gap's firing,
                            > and often puts spits large amounts of RFI and high voltage spikes
                            back
                            > toward the variac. Only recently (within the last ten years or so)
                            > have Tesla coil enthusiasts started building solid state controls
                            that
                            > will handle a large (several kilowatts or more) Tesla coil without
                            > breaking.
                            >
                            > > I have a big microwaveoven transformer rated 2750W that i have
                            > > rewound the secondary on. After that so did i get 5.4V and 1036A
                            with
                            > > shorted secondary but i needed to be able to control the output
                            so i
                            > > could control the temperature on the coils. I have now build a
                            triac-
                            > > based controller for highly inductive loads like an transformer
                            are
                            > > and i can now regulate the output power and the heat of the coil
                            > > without any step from 0 to 100%. Thanks to that its meant to
                            handle
                            > > highly inductive loads so is a small 6A enough and its hardly gets
                            > > warm with an output of 100A from the transformer.
                            >
                            > One thing you will discover after you've worked with solid state
                            > switching devices for a while, especially when you're doing phase
                            > angle control of inductive loads, is that two SCRs connected back-to
                            > -back are much more reliable, and handle surges and unexpected load
                            > behavior much better than a triac. If you compare an SCR and a
                            TRIAC
                            > having identical PRV and I(f) ratings, you will find that the I(tsm)
                            > for the SCR is typically much larger than the TRIAC's.
                            >
                            > Greatly over-specifying the switching device is not the usual
                            solution.
                            > The usual (and cheaper) solution to nasty loads (provided they
                            remain
                            > generally within the safe operating area of the device) is to place
                            a
                            > snubber network (can be as simple as a capacitor and resistor in
                            > series) across the device to limit the reverse voltage rise time
                            > appearing on the device's terminals.
                            >
                            > - Bill "Gomez" Lemieux
                            >
                          • jacques savard
                            ok i untherstand all that from the begiining i am a retired specialist in electronic and I repair some vacuum system mew one and old one and like i said the
                            Message 13 of 21 , Jul 15, 2008
                              ok

                              i untherstand all that from the begiining i am a retired specialist in
                              electronic and I repair some vacuum system
                              mew one and old one

                              and like i said the old one used variable transformer and the old technic
                              still good in this case the veriable cherge in inductive and short circuit
                              type or heating element give me a go for variable transformenr nas the
                              cost is probaly need the same
                              only the finist control a bit better on tiac system

                              jack 47'N 71'W


                              > Ok, there has been a real mixup here because in Sweden so is a triac
                              > based regulator often called a variac since they do about the same
                              > thing as a transformer based depending on how you use it - control
                              > the power. The transformer based is normally not called variac but
                              > something else that describes exactly what it is.
                              >
                              > The international name is variac but it is very rarely used for the
                              > tranformer type here so i didnt got that it was the transformer based
                              > type that was meant. But then it all makes sense since some things
                              > just really didnt add up.
                              >
                              > So then just ignore all i said before since i was talking about a
                              > triac based control unit.
                              >
                              >
                              >
                              >
                              > --- In VacuumX@yahoogroups.com, Gomez Addams <gomez@...> wrote:
                              > >
                              > >
                              > > On Jul 14, 2008, at 11:23 AM, henry_3507 wrote:
                              > >
                              > > > I read that there are problems controlling highly inductive loads
                              > > > with a simple variac since they break. There is a reason for this:
                              > > > they are not meant to be used with inductive loads, only resistive
                              > > > loads like lamps. The simple schematic that these variacs
                              > normally is
                              > > > built around isnt constructed to be used with inductive loads and
                              > > > could, depending on the load, be quickly destroyed. If a really
                              > heavy
                              > > > duty variac is used so will it hold just because the triac in it
                              > is
                              > > > bigger.
                              > >
                              > > There's something I'm missing here.
                              > >
                              > > 1. There is no triac in a variac. "Variac" is one of several
                              > trademarks
                              > > for a variable transformer. "Powerstat" is another. A triac is a
                              > solid
                              > > state switching device. You would not normally find one in or even
                              > > associated with, a variable transformer.
                              > >
                              > > 2. Variable transformers are generally MUCH more robust and rugged
                              > than
                              > > solid state switching devices.
                              > >
                              > > For decades, I and many other Tesla coil enthusiasts have been using
                              > > variable transformers to control one of the worst (from an
                              > electrical
                              > > standpoint) loads there is - disruptive discharge, spark gap type
                              > Tesla
                              > > coils. The load is intermittent, highly inductive (due to large
                              > high
                              > > voltage transformers) is intermittent due to the spark gap's firing,
                              > > and often puts spits large amounts of RFI and high voltage spikes
                              > back
                              > > toward the variac. Only recently (within the last ten years or so)
                              > > have Tesla coil enthusiasts started building solid state controls
                              > that
                              > > will handle a large (several kilowatts or more) Tesla coil without
                              > > breaking.
                              > >
                              > > > I have a big microwaveoven transformer rated 2750W that i have
                              > > > rewound the secondary on. After that so did i get 5.4V and 1036A
                              > with
                              > > > shorted secondary but i needed to be able to control the output
                              > so i
                              > > > could control the temperature on the coils. I have now build a
                              > triac-
                              > > > based controller for highly inductive loads like an transformer
                              > are
                              > > > and i can now regulate the output power and the heat of the coil
                              > > > without any step from 0 to 100%. Thanks to that its meant to
                              > handle
                              > > > highly inductive loads so is a small 6A enough and its hardly gets
                              > > > warm with an output of 100A from the transformer.
                              > >
                              > > One thing you will discover after you've worked with solid state
                              > > switching devices for a while, especially when you're doing phase
                              > > angle control of inductive loads, is that two SCRs connected back-to
                              > > -back are much more reliable, and handle surges and unexpected load
                              > > behavior much better than a triac. If you compare an SCR and a
                              > TRIAC
                              > > having identical PRV and I(f) ratings, you will find that the I(tsm)
                              > > for the SCR is typically much larger than the TRIAC's.
                              > >
                              > > Greatly over-specifying the switching device is not the usual
                              > solution.
                              > > The usual (and cheaper) solution to nasty loads (provided they
                              > remain
                              > > generally within the safe operating area of the device) is to place
                              > a
                              > > snubber network (can be as simple as a capacitor and resistor in
                              > > series) across the device to limit the reverse voltage rise time
                              > > appearing on the device's terminals.
                              > >
                              > > - Bill "Gomez" Lemieux
                              > >
                              >
                              >
                              >
                              > ------------------------------------
                              >
                              > Yahoo! Groups Links
                              >
                              >
                              >
                            • henry_3507
                              Ah ok, then i told anybody else that might wonder. Im electronic educationed as well. For those who doesnt relly know; There is a big different on the output
                              Message 14 of 21 , Jul 15, 2008
                                Ah ok, then i told anybody else that might wonder. Im electronic
                                educationed as well.

                                For those who doesnt relly know; There is a big different on the
                                output from the triac based and transformer based and they both have
                                advantages and disadvantages. With the transformer based so could you
                                regulate the output sinewave amplitude perfectly and still have a
                                nice sinuswave all the time which could be absolutely crucial for
                                some things, but these types weigh quit much and take up some room.
                                The triac based is very small even those that could handle a lot of
                                power but they doesnt change the sinuswave amplitude but instead sort
                                of hacking the sinuswave up so they control the overall power instead.

                                Both will work just fine to heat an coil in a vacuum system (with an
                                transformer between that can ramp the current up) but the triac based
                                is so much easier to build and if you would buy one so wouldnt it
                                cost as much as the transformer based, especially not if higher power
                                levels are involved.

                                I have also build a little bigger triac based one for highly
                                inductive or resistive loads that can handle up to 24KW but it isnt
                                much bigger then the palm of a hand, and it is the cooling fins that
                                take up all the place without the fins so would it be smaller than a
                                hand. A transformer based one for 24KW would cost a lot of money take
                                up a lot of room and weigh i dont know how much.



                                --- In VacuumX@yahoogroups.com, jacques savard <jacquessavard@...>
                                wrote:
                                >
                                > ok
                                >
                                > i untherstand all that from the begiining i am a retired
                                specialist in
                                > electronic and I repair some vacuum system
                                > mew one and old one
                                >
                                > and like i said the old one used variable transformer and the old
                                technic
                                > still good in this case the veriable cherge in inductive and
                                short circuit
                                > type or heating element give me a go for variable transformenr
                                nas the
                                > cost is probaly need the same
                                > only the finist control a bit better on tiac system
                                >
                                > jack 47'N 71'W
                                >
                                >
                                > > Ok, there has been a real mixup here because in Sweden so is a
                                triac
                                > > based regulator often called a variac since they do about the same
                                > > thing as a transformer based depending on how you use it - control
                                > > the power. The transformer based is normally not called variac but
                                > > something else that describes exactly what it is.
                                > >
                                > > The international name is variac but it is very rarely used for
                                the
                                > > tranformer type here so i didnt got that it was the transformer
                                based
                                > > type that was meant. But then it all makes sense since some things
                                > > just really didnt add up.
                                > >
                                > > So then just ignore all i said before since i was talking about a
                                > > triac based control unit.
                                > >
                                > >
                                > >
                                > >
                                > > --- In VacuumX@yahoogroups.com, Gomez Addams <gomez@> wrote:
                                > > >
                                > > >
                                > > > On Jul 14, 2008, at 11:23 AM, henry_3507 wrote:
                                > > >
                                > > > > I read that there are problems controlling highly inductive
                                loads
                                > > > > with a simple variac since they break. There is a reason for
                                this:
                                > > > > they are not meant to be used with inductive loads, only
                                resistive
                                > > > > loads like lamps. The simple schematic that these variacs
                                > > normally is
                                > > > > built around isnt constructed to be used with inductive loads
                                and
                                > > > > could, depending on the load, be quickly destroyed. If a
                                really
                                > > heavy
                                > > > > duty variac is used so will it hold just because the triac in
                                it
                                > > is
                                > > > > bigger.
                                > > >
                                > > > There's something I'm missing here.
                                > > >
                                > > > 1. There is no triac in a variac. "Variac" is one of several
                                > > trademarks
                                > > > for a variable transformer. "Powerstat" is another. A triac
                                is a
                                > > solid
                                > > > state switching device. You would not normally find one in or
                                even
                                > > > associated with, a variable transformer.
                                > > >
                                > > > 2. Variable transformers are generally MUCH more robust and
                                rugged
                                > > than
                                > > > solid state switching devices.
                                > > >
                                > > > For decades, I and many other Tesla coil enthusiasts have been
                                using
                                > > > variable transformers to control one of the worst (from an
                                > > electrical
                                > > > standpoint) loads there is - disruptive discharge, spark gap
                                type
                                > > Tesla
                                > > > coils. The load is intermittent, highly inductive (due to large
                                > > high
                                > > > voltage transformers) is intermittent due to the spark gap's
                                firing,
                                > > > and often puts spits large amounts of RFI and high voltage
                                spikes
                                > > back
                                > > > toward the variac. Only recently (within the last ten years or
                                so)
                                > > > have Tesla coil enthusiasts started building solid state
                                controls
                                > > that
                                > > > will handle a large (several kilowatts or more) Tesla coil
                                without
                                > > > breaking.
                                > > >
                                > > > > I have a big microwaveoven transformer rated 2750W that i have
                                > > > > rewound the secondary on. After that so did i get 5.4V and
                                1036A
                                > > with
                                > > > > shorted secondary but i needed to be able to control the
                                output
                                > > so i
                                > > > > could control the temperature on the coils. I have now build a
                                > > triac-
                                > > > > based controller for highly inductive loads like an
                                transformer
                                > > are
                                > > > > and i can now regulate the output power and the heat of the
                                coil
                                > > > > without any step from 0 to 100%. Thanks to that its meant to
                                > > handle
                                > > > > highly inductive loads so is a small 6A enough and its hardly
                                gets
                                > > > > warm with an output of 100A from the transformer.
                                > > >
                                > > > One thing you will discover after you've worked with solid state
                                > > > switching devices for a while, especially when you're doing
                                phase
                                > > > angle control of inductive loads, is that two SCRs connected
                                back-to
                                > > > -back are much more reliable, and handle surges and unexpected
                                load
                                > > > behavior much better than a triac. If you compare an SCR and a
                                > > TRIAC
                                > > > having identical PRV and I(f) ratings, you will find that the I
                                (tsm)
                                > > > for the SCR is typically much larger than the TRIAC's.
                                > > >
                                > > > Greatly over-specifying the switching device is not the usual
                                > > solution.
                                > > > The usual (and cheaper) solution to nasty loads (provided they
                                > > remain
                                > > > generally within the safe operating area of the device) is to
                                place
                                > > a
                                > > > snubber network (can be as simple as a capacitor and resistor in
                                > > > series) across the device to limit the reverse voltage rise time
                                > > > appearing on the device's terminals.
                                > > >
                                > > > - Bill "Gomez" Lemieux
                                > > >
                                > >
                                > >
                                > >
                                > > ------------------------------------
                                > >
                                > > Yahoo! Groups Links
                                > >
                                > >
                                > >
                                >
                              • glinos7124
                                ... How about some examples. Block diagrams of working systems?? I m thinking of building a coater but I m not an expert at high amperage circuits. tom
                                Message 15 of 21 , Jul 16, 2008
                                  --- In VacuumX@yahoogroups.com, jacques savard <jacquessavard@...>

                                  How about some examples.

                                  Block diagrams of working systems??

                                  I'm thinking of building a coater but I'm not an expert
                                  at high amperage circuits.

                                  tom
                                • Ken Hunter
                                  ... Tom, Look in the Groups Files section for the Strong article and the system description just below for starter info. There is a lot of info oin that
                                  Message 16 of 21 , Jul 17, 2008
                                    --- In VacuumX@yahoogroups.com, "glinos7124" <tg@...> wrote:
                                    >
                                    > --- In VacuumX@yahoogroups.com, jacques savard <jacquessavard@>
                                    >
                                    > How about some examples.
                                    >
                                    > Block diagrams of working systems??


                                    Tom,

                                    Look in the Groups "Files" section for the Strong article and the
                                    system description just below for starter info. There is a lot of info
                                    oin that folder for you to check out.

                                    Ken Hunter
                                    VacuumX Group owner
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