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More interesting Aluminum tidbits

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  • Zulaware
    Apparently mercury breaks down the oxide layer and can make Al dissolve. Reportedly Hg paste was used to sabotage WWII German planes. Also the oxide layer
    Message 1 of 16 , Oct 1, 2004
      Apparently mercury breaks down the oxide layer and can make Al
      "dissolve." Reportedly Hg paste was used to sabotage WWII German
      planes. Also the oxide layer is chemically similar to sapphire

      http://www.popsci.com/popsci/h20/article/0,12543,693558,00.html
    • Ed Phillips
      Apparently mercury breaks down the oxide layer and can make Al dissolve. Reportedly Hg paste was used to sabotage WWII German planes. Also the oxide layer
      Message 2 of 16 , Oct 1, 2004
        "Apparently mercury breaks down the oxide layer and can make Al
        "dissolve." Reportedly Hg paste was used to sabotage WWII German
        planes. Also the oxide layer is chemically similar to sapphire"

        What actually happens is that the mercury flows between the crystalline
        grains of aluminum alloys (suspect pure aluminum is safe) and weakens
        the "joints". Back in the 1950's there was an investigation into the
        use of mercury in projectiles to enhance their effect in air-to-air
        attacks. I ran some experiments of my own at the time, using mercury
        with a bit of zinc dissolved in it. I had some aluminum extrusions
        (actually file cabinet locking bars) and found that when I scratched
        through the oxide in one spot about 18" from the end and rubbed the
        amalgam into it the end would fall off of its own weight (bar
        horizontal) in a few seconds; the resulting broken surface was rough and
        grey with fine white crystals on it and the metal at that point was
        warm. Easy enough to try.

        Ed
      • Jim Farrer
        Sounds like the mercury is acting like a catalyst -- participates in the chemical activity, but emerges unchanged at the end, ready to particpate all over
        Message 3 of 16 , Oct 2, 2004
          Sounds like the mercury is acting like a catalyst -- participates in the
          chemical activity, but
          emerges unchanged at the end, ready to particpate all over again.

          I understand that hydrofluoric acid is like this. GOD Forbid that a
          tiny amount of HF gets under
          your fingernail. Just keeps eating and eating. YUK.

          Jim Farrer


          Ed Phillips wrote:

          > "Apparently mercury breaks down the oxide layer and can make Al
          > "dissolve." Reportedly Hg paste was used to sabotage WWII German
          > planes. Also the oxide layer is chemically similar to sapphire"
          >
          > What actually happens is that the mercury flows between the
          > crystalline
          > grains of aluminum alloys (suspect pure aluminum is safe) and weakens
          > the "joints". Back in the 1950's there was an investigation into the
          > use of mercury in projectiles to enhance their effect in air-to-air
          > attacks. I ran some experiments of my own at the time, using mercury
          > with a bit of zinc dissolved in it. I had some aluminum extrusions
          > (actually file cabinet locking bars) and found that when I scratched
          > through the oxide in one spot about 18" from the end and rubbed the
          > amalgam into it the end would fall off of its own weight (bar
          > horizontal) in a few seconds; the resulting broken surface was rough and
          > grey with fine white crystals on it and the metal at that point was
          > warm. Easy enough to try.
          >
          > Ed
          >
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        • dongibbs
          I m sure everyone is aware how hazardous mercury and HF are. Exercise EXTREME CARE is using either one. What may not be widely known is Whink, the stuff
          Message 4 of 16 , Oct 3, 2004
            I'm sure everyone is aware how hazardous mercury and HF are. Exercise
            EXTREME CARE is using either one.

            What may not be widely known is Whink, the stuff widely sold as a rust
            remover actually contains HF acid. While not listed in the contents, the
            large skull and crossbones warning is real.

            My wife used this stuff without gloves and when her hands began to swell,
            she called the poison center. They told her to get to an emergency room
            immediately. The Hydrofluoric acid keeps penetrating until it neutralizes
            itself on the calcium in your bones. The ER gave her calcium shots in each
            finger tip and between each finger with no antithetic, about 50 shots
            total. (I would have died from the shock and pain). Fortunately she didn't
            seem to have any permanent effects. We threw the Whink out right away.

            Mercury can also be absorbed through the skin and should be handled with
            extreme care.

            I suspect we all get careless because of all the superficial warnings on
            everything due to all the lawsuits. I fully expect that bottled water will
            someday have a warning like 'Do not immerse head in this for long periods of
            time'.

            But, joking aside, some warnings are real. Please be careful. Pay special
            attention to a skull and crossbones.

            Best Regards,

            Don Gibbs





            ----- Original Message -----
            From: "Jim Farrer" <jfarrer@...>
            To: <usa-tesla@yahoogroups.com>
            Sent: Saturday, October 02, 2004 8:34 AM
            Subject: Re: [usa-tesla] More interesting Aluminum tidbits


            >
            > Sounds like the mercury is acting like a catalyst -- participates in the
            > chemical activity, but
            > emerges unchanged at the end, ready to particpate all over again.
            >
            > I understand that hydrofluoric acid is like this. GOD Forbid that a
            > tiny amount of HF gets under
            > your fingernail. Just keeps eating and eating. YUK.
            >
            > Jim Farrer

            <snip>
          • Jim Farrer
            Thanks for this heads up on Whink, Don! What a bad product, and with no warnings, especially no content listing. Goes to prove that all of our enemies are
            Message 5 of 16 , Oct 3, 2004
              Thanks for this heads up on Whink, Don! What a bad product, and with no
              warnings, especially no content listing. Goes to prove that all of our
              enemies
              are not just the terrorists.

              I think that mercury and asbestos are way overblown as hazards. I breathed
              lots and lots of asbestos dust for 15 years: no ill effect. This was in
              (a) my home,
              with asbestos insulation of furnace ducts, pipes, etc. and (b) family
              business neon
              sign shop, with its hundreds of asbestos patterns for tube bending.
              Glass applied red hot to the pattern for fitting. Hundreds of patterns
              on a bench
              top, lifted off, placed on floor, looking for a particular pattern,
              going down through
              TWO INCHES of asbestos. I did *all* of this for Dad, he didn't have
              time to.
              Kept me occupied, off the streets, out of trouble.

              We had a McCleod mercury gauge, containing some 15 pounds of mercury, and
              3 ceramic vessels with another 30 pounds or so. Several of us kids
              played with
              mercury on our hands, rubbing a penny to make it look lime a dime. No
              one ever got ill.

              TODAY? HAH !!! If you so much as break a mercury thermometer, the
              riot sq
              uhhhh- hazmat squad is called, they evacuate the premises, then spend
              days trying to
              recover every tiny little bead of the stuff. [It's up to you to find
              your own place to live.]

              I have a one pound bottle of mercury; have had it for 20 years. Over
              the years and
              various projects (like a handblown pyrex glass, 4 port vacuum guage
              for use on our
              Honda 500, 4 cyl motorcycle), and have lost maybe an entire teaspoon of
              mercury
              in the basement. I don't worry myself sick about this looming horrible
              poison.

              Despite what is said above, I HIGHLY respect mercury, and do my utmost
              to not lose
              any of it. It is kept carefully hidden away, where it will never get
              its glass jar broken.

              If the city of Rockville, MD. were to know this, I'd probably be put in
              jail for the
              rest of my life if I lived that long.

              Jim Farrer
              P.S.: But the story of that Wink stuff is MOST unsettling.
              HORRIFYING, even.


              dongibbs wrote:

              > I'm sure everyone is aware how hazardous mercury and HF are. Exercise
              > EXTREME CARE is using either one.
              >
              > What may not be widely known is Whink, the stuff widely sold as a rust
              > remover actually contains HF acid. While not listed in the contents, the
              > large skull and crossbones warning is real.
              >
              > My wife used this stuff without gloves and when her hands began to
              > swell,
              > she called the poison center. They told her to get to an emergency room
              > immediately. The Hydrofluoric acid keeps penetrating until it
              > neutralizes
              > itself on the calcium in your bones. The ER gave her calcium shots in
              > each
              > finger tip and between each finger with no antithetic, about 50 shots
              > total. (I would have died from the shock and pain). Fortunately she
              > didn't
              > seem to have any permanent effects. We threw the Whink out right away.
              >
              > Mercury can also be absorbed through the skin and should be handled with
              > extreme care.
              >
              > I suspect we all get careless because of all the superficial warnings on
              > everything due to all the lawsuits. I fully expect that bottled water
              > will
              > someday have a warning like 'Do not immerse head in this for long
              > periods of
              > time'.
              >
              > But, joking aside, some warnings are real. Please be careful. Pay
              > special
              > attention to a skull and crossbones.
              >
              > Best Regards,
              >
              > Don Gibbs
              >
              >
              >
              >
              >
              > ----- Original Message -----
              > From: "Jim Farrer" <jfarrer@...>
              > To: <usa-tesla@yahoogroups.com>
              > Sent: Saturday, October 02, 2004 8:34 AM
              > Subject: Re: [usa-tesla] More interesting Aluminum tidbits
              >
              >
              > >
              > > Sounds like the mercury is acting like a catalyst -- participates in the
              > > chemical activity, but
              > > emerges unchanged at the end, ready to particpate all over again.
              > >
              > > I understand that hydrofluoric acid is like this. GOD Forbid that a
              > > tiny amount of HF gets under
              > > your fingernail. Just keeps eating and eating. YUK.
              > >
              > > Jim Farrer
              >
              > <snip>
              >
              >
              >
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            • Island Roamer
              Fast question, when it comes to a tesla coil what is the best frequency to use that gives the biggest output...?
              Message 6 of 16 , Oct 3, 2004
                Fast question, when it comes to a tesla coil what is
                the best frequency to use that gives the biggest
                output...?



                ______________________________________________________________________
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              • Bert Hickman
                Hello, There are no magic frequencies that will provide markedly better Tesla Coil performance. For any size coil you will always get the best output when the
                Message 7 of 16 , Oct 4, 2004
                  Hello,

                  There are no magic frequencies that will provide markedly better Tesla
                  Coil performance. For any size coil you will always get the best
                  output when the primary and secondary resonant circuits are in "tune".
                  This means that the product of the inductance and capacitance in the
                  primary circuit equals that in the secondary circuit (LpCp = LsCs) and
                  the primary or secondary LC circuit would oscillate at, or near, the
                  same "natural" frequency.

                  In addition, it's been found (empirically) that streamers propagate
                  better as you use larger toploads/toroids (higher Cs) and larger
                  diameter secondaries (higher Ls). However, the system must also be
                  "sized" to match the amount of power available from the HV power
                  source. A large coil driven by a power supply that is too small will
                  not generate any sparks at all if there is insufficient energy to
                  cause the system to "break out" - i.e., form initial streamers.
                  Getting the longest sparks for a given power level is a bit of a
                  balancing act that requires some trial and error experimentation with
                  toroid size, Primary to Secondary coupling, and tuning.

                  For small, low power coils (0-500 watts), the "sweet spot" seems to be
                  between 150-300 kHz. Medium sized coils (500-3000 watts) seem to run
                  best between 80 and 200 kHz, and large coils (above 3000 watts)
                  typically operate best in the 45-100 kHz range. For a given power
                  level, the lower the frequency, the better the performance seems to be.

                  Best regards,

                  -- Bert --
                  --
                  ---------------------------------------------------------------------
                  We specialize in UNIQUE items! Coins shrunk by huge magnetic fields,
                  Lichtenberg Figures ("Captured Lightning" in acrylic), & Out-of-Print
                  technical Books. Stoneridge Engineering - http://www.teslamania.com
                  ---------------------------------------------------------------------

                  Island Roamer wrote:

                  >
                  > Fast question, when it comes to a tesla coil what is
                  > the best frequency to use that gives the biggest
                  > output...?
                  >
                  >
                  >
                  > ______________________________________________________________________
                  > Post your free ad now! http://personals.yahoo.ca
                  >
                  >
                  >
                  >
                  > Yahoo! Groups Links
                  >
                  >
                  >
                  >
                  >
                  >
                  >
                  > .
                  >
                • Paul Eitson
                  ... What would be an easy method to determine the product of the inductance and capacitance in the primary and secondary circuits? Paul
                  Message 8 of 16 , Oct 9, 2004
                    On Oct 4, 2004, at 9:52 AM, Bert Hickman wrote:

                    > Hello,
                    >
                    > There are no magic frequencies that will provide markedly better Tesla
                    > Coil performance. For any size coil you will always get the best
                    > output when the primary and secondary resonant circuits are in "tune".
                    > This means that the product of the inductance and capacitance in the
                    > primary circuit equals that in the secondary circuit (LpCp = LsCs) and
                    > the primary or secondary LC circuit would oscillate at, or near, the
                    > same "natural" frequency.
                    >
                    > -- Bert --

                    What would be an easy method to determine the product of the
                    inductance and capacitance in the primary and secondary circuits?
                    Paul
                  • Bert Hickman
                    ... Hi Paul, By either measuring the individual L and C values (easy for the primary alone using an inexpensive hand held RLC meter) or by measuring the
                    Message 9 of 16 , Oct 10, 2004
                      Paul Eitson wrote:

                      >
                      >
                      > On Oct 4, 2004, at 9:52 AM, Bert Hickman wrote:
                      >
                      > Hello,
                      >
                      > There are no magic frequencies that will provide markedly better Tesla
                      > Coil performance. For any size coil you will always get the best
                      > output when the primary and secondary resonant circuits are in "tune".
                      > This means that the product of the inductance and capacitance in the
                      > primary circuit equals that in the secondary circuit (LpCp = LsCs) and
                      > the primary or secondary LC circuit would oscillate at, or near, the
                      > same "natural" frequency.
                      >
                      > -- Bert --
                      >
                      >
                      > What would be an easy method to determine the product of the
                      > inductance and capacitance in the primary and secondary circuits?
                      > Paul
                      >

                      Hi Paul,

                      By either measuring the individual L and C values (easy for the
                      primary alone using an inexpensive hand held RLC meter) or by
                      measuring the natural resonant frequencies of the isolated primary and
                      secondary circuits using a signal generator that can cover the range
                      of 20 kHz - 1 MHz. An even simpler (and less expensive) way is to use
                      a Tesla Coil design program to calculate the values using physically
                      measured parameters of your Tesla coil.

                      When in tune, Lp*Cp = Ls*Cs. What this REALLY means is that when the
                      primary and secondary resonant frequencies are the same (Fp = Fs) the
                      Tesla Coil is in tune. The following procedure will bring the system
                      into "instrument tune" - and once the coil is powered up, minor
                      changes are then made to tune for best performance. Tweaks are
                      typically necessary to adjust for spark loading, and then coupling
                      (we want highest primary-to-secondary coupling without generating
                      racing sparks on the secondary).

                      The easiest way is to measure Fp and Fs is to use a signal generator
                      and a pair of back-to-back LED's (LED's in parallel but at opposite
                      polarities). Measure the secondary first by positioning it where it
                      will be in normal operation with respect to the primary. Make sure
                      that the secondary top load (toroid) is also positioned on top of the
                      secondary. Disconnect the primary capacitor and connect ONE end of the
                      primary to earth ground. Connect the signal output from the signal
                      generator to the bottom lead of the secondary through the back-to-back
                      LED's and ground the other signal generator output lead. Slowly sweep
                      the frequency upwards from the lowest setting looking for the first
                      current peak (the lowest frequency where the LED's light the
                      brightest). Reduce the signal generator's output amplitude if
                      necessary to narrow down the natural resonant frequency of the
                      secondary LC system (Fs). Once this is complete, disconnect the
                      secondary and place it in another room (far from the primary).

                      For the primary circuit, the signal generator is connected through the
                      LED's to the series combination of the primary inductor and capacitor.
                      Make sure that the HV power source, ann any protective filters are
                      electrically disconnected from the primary circuit. Starting at the
                      lowest frequency, slowly sweep upwards looking for the frequency that
                      draws the most current (highest LED brightness) - this will be the
                      primary frequency Fp. Adjust the inductance of the primary (by
                      tapping) or the capacitance (by adding or removing capacitance) until
                      the primary's resonant frequency is the same as that measured for the
                      secondary (set Fp = Fs). The primary should now be "instrument tuned"
                      to the secondary. The secondary can now be positioned with the primary
                      and the coil then carefully adjusted to get the best spark under power.

                      An even easier approach is to use a Tesla Coil design tool (JavaTC,
                      FANTC, TCPlan). These are now powerful enough to allow you do get very
                      close to proper tune by simply plugging in your coil's physical
                      measurements and component values. You can use any of these programs
                      to predict where the primary tap should be located and tune for best
                      spark from that point. Some of the best Tesla Coil design tools follow:
                      http://www.classictesla.com/java/javatc.html
                      http://www.classictesla.com/fantc/fantc.html
                      http://home.datacomm.ch/k.schraner/spreadsheets.htm

                      A couple of excellent beginner's sites that cover details of coil
                      design include Deep Fried Neon (UK) and Matt Behrand's Tesla Coil Web
                      Site:
                      http://www.deepfriedneon.com/tesla_frame0.html
                      http://home.earthlink.net/%7Eelectronxlc/

                      And once you become more knowledgeable, Richie Burnett's site is
                      probably one of the best on the web:
                      http://www.richieburnett.co.uk/

                      Good luck and best regards,

                      -- Bert --
                      --
                      ---------------------------------------------------------------------
                      We specialize in UNIQUE items! Coins shrunk by huge magnetic fields,
                      Lichtenberg Figures ("Captured Lightning" in acrylic), & Out-of-Print
                      technical Books. Stoneridge Engineering - http://www.teslamania.com
                      ---------------------------------------------------------------------
                    • Paul Eitson
                      Thank you I will print this out and examine it in detail. Paul
                      Message 10 of 16 , Oct 10, 2004
                        Thank you I will print this out and examine it in detail.
                        Paul

                        On Oct 10, 2004, at 8:40 AM, Bert Hickman wrote:

                        > Paul Eitson wrote:
                        >
                        > >
                        > >
                        > > On Oct 4, 2004, at 9:52 AM, Bert Hickman wrote:
                        > >
                        > >     Hello,
                        > >
                        > >     There are no magic frequencies that will provide markedly
                        > better Tesla
                        > >     Coil performance. For any size coil you will always get the best
                        > >     output when the primary and secondary resonant circuits are in
                        > "tune".
                        > >     This means that the product of the inductance and capacitance
                        > in the
                        > >     primary circuit equals that in the secondary circuit (LpCp =
                        > LsCs) and
                        > >     the primary or secondary LC circuit would oscillate at, or
                        > near, the
                        > >     same "natural" frequency.
                        > >
                        > >     -- Bert --
                        > >
                        > >
                        > > What would be an easy method to determine the product of the
                        > > inductance and capacitance in the primary and secondary circuits?
                        > > Paul
                        > >
                        >
                        > Hi Paul,
                        >
                        > By either measuring the individual L and C values (easy for the
                        > primary alone using an inexpensive hand held RLC meter) or by
                        > measuring the natural resonant frequencies of the isolated primary and
                        > secondary circuits using a signal generator that can cover the range
                        > of 20 kHz - 1 MHz. An even simpler (and less expensive) way is to use
                        > a Tesla Coil design program to calculate the values using physically
                        > measured parameters of your Tesla coil.
                        >
                        > When in tune, Lp*Cp = Ls*Cs. What this REALLY means is that when the
                        > primary and secondary resonant frequencies are the same (Fp = Fs) the
                        > Tesla Coil is in tune. The following procedure will bring the system
                        > into "instrument tune" - and once the coil is powered up, minor
                        > changes are then made to tune for best performance. Tweaks are
                        > typically necessary  to adjust for spark loading, and then coupling
                        > (we want highest primary-to-secondary coupling without generating
                        > racing sparks on the secondary).
                        >
                        > The easiest way is to measure Fp and Fs is to use a signal generator
                        > and a pair of back-to-back LED's (LED's in parallel but at opposite
                        > polarities). Measure the secondary first by positioning it where it
                        > will be in normal operation with respect to the primary. Make sure
                        > that the secondary top load (toroid) is also positioned on top of the
                        > secondary. Disconnect the primary capacitor and connect ONE end of the
                        > primary to earth ground. Connect the signal output from the signal
                        > generator to the bottom lead of the secondary through the back-to-back
                        > LED's and ground the other signal generator output lead. Slowly sweep
                        > the frequency upwards from the lowest setting looking for the first
                        > current peak (the lowest frequency where the LED's light the
                        > brightest). Reduce the signal generator's output amplitude if
                        > necessary to narrow down the natural resonant frequency of the
                        > secondary LC system (Fs). Once this is complete, disconnect the
                        > secondary and place it in another room (far from the primary).
                        >
                        > For the primary circuit, the signal generator is connected through the
                        > LED's to the series combination of the primary inductor and capacitor.
                        > Make sure that the HV power source, ann any protective filters are
                        > electrically disconnected from the primary circuit. Starting at the
                        > lowest frequency, slowly sweep upwards looking for the frequency that
                        > draws the most current (highest LED brightness) - this will be the
                        > primary frequency Fp. Adjust the inductance of the primary (by
                        > tapping) or the capacitance (by adding or removing capacitance) until
                        > the primary's resonant frequency is the same as that measured for the
                        > secondary (set Fp = Fs). The primary should now be "instrument tuned"
                        > to the secondary. The secondary can now be positioned with the primary
                        > and the coil then carefully adjusted to get the best spark under
                        > power.
                        >
                        > An even easier approach is to use a Tesla Coil design tool (JavaTC,
                        > FANTC, TCPlan). These are now powerful enough to allow you do get very
                        > close to proper tune by simply plugging in your coil's physical
                        > measurements and component values. You can use any of these programs
                        > to predict where the primary tap should be located and tune for best
                        > spark from that point. Some of the best Tesla Coil design tools
                        > follow:
                        > http://www.classictesla.com/java/javatc.html
                        > http://www.classictesla.com/fantc/fantc.html
                        > http://home.datacomm.ch/k.schraner/spreadsheets.htm
                        >
                        > A couple of excellent beginner's sites that cover details of coil
                        > design include Deep Fried Neon (UK) and Matt Behrand's Tesla Coil Web
                        > Site:
                        > http://www.deepfriedneon.com/tesla_frame0.html
                        > http://home.earthlink.net/%7Eelectronxlc/
                        >
                        > And once you become more knowledgeable, Richie Burnett's site is
                        > probably one of the best on the web:
                        > http://www.richieburnett.co.uk/
                        >
                        > Good luck and best regards,
                        >
                        > -- Bert --
                        > --
                        > ---------------------------------------------------------------------
                        > We specialize in UNIQUE items! Coins shrunk by huge magnetic fields,
                        > Lichtenberg Figures ("Captured Lightning" in acrylic), & Out-of-Print
                        > technical Books. Stoneridge Engineering - http://www.teslamania.com
                        > ---------------------------------------------------------------------
                        >
                        >
                        >
                        >
                        > Yahoo! Groups Sponsor
                        >
                        > ADVERTISEMENT
                        > <81804_0704_b_300250a.gif>
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                        >
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                        >  
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                      • Paul Eitson
                        The following diagram is a simplified view of a multi-disk generator. Stainless steel rotors are separated by high dielectric spacers and bolted to hubs which
                        Message 11 of 16 , Oct 13, 2004
                          The following diagram is a simplified view of a multi-disk
                          generator. Stainless steel rotors are separated by high dielectric
                          spacers and bolted to hubs which are locked to a shaft. Field is
                          supplied by a combination of electro and permanent magnets which
                          completely cover the outside 1/3 of the disk surface. Current is drawn
                          off the disks individually or collectively with highs speed graphite
                          brushes. Disks can be connected to the shaft collectively or
                          individually via a set of copper filled grooves on the shaft. Any one
                          interested in construction of this or a similar project I am working on
                          please contact me. Paul
                        • McGalliard, Frederick B
                          Paul. I was thinking of a generator operating in the RF. There are two ways to do this. One can take a disk in a number of pi sections, making a multi plate
                          Message 12 of 16 , Oct 13, 2004
                            Paul. I was thinking of a generator operating in the RF. There are two
                            ways to do this. One can take a disk in a number of pi sections, making
                            a multi plate capacitor that increases and decreases as the disk
                            rotates. You can pump charge, like a vandergraf, or use a leading
                            capacitance change to kick an AC excitation up a bit. A bit more fun
                            than a more ordinary generator.

                            I was trying to figure out how to make the rotating plate drag a
                            magnetic loop across the coil I would use to generate signal. This might
                            be more powerful.

                            > -----Original Message-----
                            > From: Paul Eitson [mailto:teslat3@...]
                            > Subject: [usa-tesla] Multi-disk generator diagram
                            ...
                            > The following diagram is a simplified view of a multi-disk
                            > generator.
                          • Bert Hickman
                            Hello Paul, Although it varies considerably by alloy, stainless steel alloys have considerably higher electrical resistivity than copper. The voltage drop
                            Message 13 of 16 , Oct 13, 2004
                              Hello Paul,

                              Although it varies considerably by alloy, stainless steel alloys have
                              considerably higher electrical resistivity than copper. The voltage
                              drop across the rotor will be a directly proportional to the rotor's
                              resistivity. For example, the resistivity of 904L stainless is about
                              4.8x10-4 ohm-cm compared to copper at 1.724x10-6 ohm-cm. This means
                              that the voltage drop and joule heating will be ~278 times greater
                              than copper.

                              This could be a major problem in your application since the EMF is
                              relatively low versus rotational speed for homopolar generators. As a
                              result, with stainless steel rotors the generator's output voltage
                              will rapidly collapse as you try to pull current from the device. To
                              reduce flywheel tensile forces and resistive losses, you may wish to
                              consider another metal, such as a high strength aluminum alloy. For
                              example, aluminum 7075 alloy has one of the highest strength to weight
                              ratios of all aluminum alloys, and has a resistivity of about
                              5.15x10-6 ohm-cm (only about 3X that of copper). However its high
                              tensile strength (48,000 psi) and light weight should allow much
                              higher rotational speeds than copper. However, you may need to weld a
                              copper outer ring onto the rotors since aluminum does not make a good
                              commutator surface.

                              Since the rotor to rotor potential will be nearly zero at all points,
                              what benefit do the dielectric spacers provide?

                              What is your intended application?

                              Good luck and best regards,

                              -- Bert --
                              --
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                              Paul Eitson wrote:
                              > The following diagram is a simplified view of a multi-disk
                              > generator. Stainless steel rotors are separated by high dielectric
                              > spacers and bolted to hubs which are locked to a shaft. Field is
                              > supplied by a combination of electro and permanent magnets which
                              > completely cover the outside 1/3 of the disk surface. Current is drawn
                              > off the disks individually or collectively with highs speed graphite
                              > brushes. Disks can be connected to the shaft collectively or
                              > individually via a set of copper filled grooves on the shaft. Any one
                              > interested in construction of this or a similar project I am working on
                              > please contact me. Paul
                              >
                              >
                              >
                              >
                              > Yahoo! Groups Links
                              >
                              >
                              >
                              >
                            • Paul Eitson
                              As always most astute observations. I have been looking into a copper coating on the disks, however they are too large for the platers I have contacted. I will
                              Message 14 of 16 , Oct 13, 2004
                                As always most astute observations. I have been looking into a
                                copper coating on the disks, however they are too large for the platers
                                I have contacted. I will look into plating them myself, if the
                                procedure is not too complicated, costly , or otherwise an undesirable
                                project. In answer to some of your questions, the high dielectric
                                spacers were to prevent conduction between plates in the event current
                                is to be drawn off separately from each disk. This would allow each
                                disk to alternately be tapped for charge. Imagine if you would a
                                separate conductive path for each disk , at even intervals around the
                                shaft. When a brush comes in contact with that path, it pulls current
                                form only one of 5 disks. This happens 5 times per rotation. At 4000
                                rpm this would be 20,000 DC pulses per minute. I do not know if my
                                figures are correct, but for copper disks the voltage and amperage are
                                somewhere around 30V and 300 amp per disk.
                                What is your intended application?
                                The drawing is merely an illustration to communicate a method to
                                create a multidisk generator. I do not have an intended application,
                                but it seems like it may be a useful item for welding. I will not have
                                time for this actual project for many years to come so if anyone else
                                wants to work on it in the meantime, feel free. I am woking on a
                                similar project that will use magnetic field to damp vibration in a
                                multi-disk rotor section. I theorize that as charge in each disk
                                increases, it will be repelled from the increasing magnetic field,
                                which will damp the vibration in the rotors. Both Al and Cu are
                                paramagnetic so should be repelled by the field .
                                Paul

                                On Oct 13, 2004, at 5:38 PM, Bert Hickman wrote:

                                > Hello Paul,
                                >
                                > Although it varies considerably by alloy, stainless steel alloys have
                                > considerably higher electrical resistivity than copper. The voltage
                                > drop across the rotor will be a directly proportional to the rotor's
                                > resistivity. For example, the resistivity of 904L stainless is about
                                > 4.8x10-4 ohm-cm compared to copper at 1.724x10-6 ohm-cm. This means
                                > that the voltage drop and joule heating will be ~278 times greater
                                > than copper.
                                >
                                > This could be a major problem in your application since the EMF is
                                > relatively low versus rotational speed for homopolar generators. As a
                                > result, with stainless steel rotors the generator's output voltage
                                > will rapidly collapse as you try to pull current from the device. To
                                > reduce flywheel tensile forces and resistive losses, you may wish to
                                > consider another metal, such as a high strength aluminum alloy. For
                                > example, aluminum 7075 alloy has one of the highest strength to weight
                                > ratios of all aluminum alloys, and has a resistivity of about
                                > 5.15x10-6 ohm-cm (only about 3X that of copper). However its high
                                > tensile strength (48,000 psi) and light weight should allow much
                                > higher rotational speeds than copper. However, you may need to weld a
                                > copper outer ring onto the rotors since aluminum does not make a good
                                > commutator surface.
                                >
                                > Since the rotor to rotor potential will be nearly zero at all points,
                                > what benefit do the dielectric spacers provide?
                                >
                                > What is your intended application?
                                >
                                > Good luck and best regards,
                                >
                                > -- Bert --
                                > --
                                > ---------------------------------------------------------------------
                                > We specialize in UNIQUE items! Coins shrunk by huge magnetic fields,
                                > Lichtenberg Figures ("Captured Lightning" in acrylic), & Out-of-Print
                                > technical Books. Stoneridge Engineering - http://www.teslamania.com
                                > ---------------------------------------------------------------------
                                >
                                > Paul Eitson wrote:
                                > >     The following diagram is a simplified view of a multi-disk
                                > > generator. Stainless steel rotors are separated by high dielectric
                                > > spacers  and bolted to hubs which are locked to a shaft.  Field is
                                > > supplied by a combination of electro and permanent magnets which
                                > > completely cover the outside 1/3 of the disk surface.  Current is
                                > drawn
                                > > off the disks individually or collectively with highs speed graphite
                                > > brushes. Disks can be connected to the shaft  collectively or
                                > > individually via a set of copper filled grooves on the shaft.   Any
                                > one
                                > > interested in construction of this or a similar project I am
                                > working on
                                > > please contact me.  Paul
                                > >
                                > >
                                > >
                                > > 
                                > > Yahoo! Groups Links
                                > >
                                > >
                                > >
                                > > 
                                >
                                >
                                >
                                >
                                >
                                >
                                > Yahoo! Groups Sponsor
                                >
                                > ADVERTISEMENT
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                              • Paul Eitson
                                I have done some reading about the black body effect: http://en.wikipedia.org/wiki/Thermal_radiation It wold not explain the link you mention though it was
                                Message 15 of 16 , Oct 13, 2004
                                  I have done some reading about the black body effect:
                                  http://en.wikipedia.org/wiki/Thermal_radiation
                                  It wold not explain the link you mention though it was interesting. The
                                  black body effect occurs when an object reaches a temperature at which
                                  it no longer reflects light in the visible spectrum. According to my
                                  understanding of the article, this may be due to the particle wave
                                  nature of light. We can only see objects because they reflect light,
                                  and we only see a narrow band of the spectrum. When metals reach a
                                  certain temperature, they seem to interfere with the wavelength of
                                  light, pushing it to a different spectrum that is not visible to us.
                                  Paul
                                  On Oct 13, 2004, at 4:54 PM, McGalliard, Frederick B wrote:

                                  > Paul. I was thinking of a generator operating in the RF. There are two
                                  > ways to do this. One can take a disk in a number of pi sections,
                                  > making
                                  > a multi plate capacitor that increases and decreases as the disk
                                  > rotates. You can pump charge, like a vandergraf, or use a leading
                                  > capacitance change to kick an AC excitation up a bit. A bit more fun
                                  > than a more ordinary generator.
                                  >
                                  > I was trying to figure out how to make the rotating plate drag a
                                  > magnetic loop across the coil I would use to generate signal. This
                                  > might
                                  > be more powerful.
                                  >
                                  > > -----Original Message-----
                                  > > From: Paul Eitson [mailto:teslat3@...]
                                  > > Subject: [usa-tesla] Multi-disk generator diagram
                                  > ...
                                  > >     The following diagram is a simplified view of a multi-disk
                                  > > generator.
                                  >
                                  >
                                  >
                                  > Yahoo! Groups Sponsor
                                  >
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                                • Paul Eitson
                                  I am interested in this idea, I would have to do considerable thinking to visualize what you are talking about. I will attempt to draw up some diagrams if
                                  Message 16 of 16 , Oct 17, 2004
                                    I am interested in this idea, I would have to do considerable
                                    thinking to visualize what you are talking about. I will attempt to
                                    draw up some diagrams if you will let me know If I am close.
                                    Paul
                                    On Oct 13, 2004, at 4:54 PM, McGalliard, Frederick B wrote:

                                    > Paul. I was thinking of a generator operating in the RF. There are two
                                    > ways to do this. One can take a disk in a number of pi sections,
                                    > making
                                    > a multi plate capacitor that increases and decreases as the disk
                                    > rotates. You can pump charge, like a vandergraf, or use a leading
                                    > capacitance change to kick an AC excitation up a bit. A bit more fun
                                    > than a more ordinary generator.
                                    >
                                    > I was trying to figure out how to make the rotating plate drag a
                                    > magnetic loop across the coil I would use to generate signal. This
                                    > might
                                    > be more powerful.
                                    >
                                    > > -----Original Message-----
                                    > > From: Paul Eitson [mailto:teslat3@...]
                                    > > Subject: [usa-tesla] Multi-disk generator diagram
                                    > ...
                                    > >     The following diagram is a simplified view of a multi-disk
                                    > > generator.
                                    >
                                    >
                                    >
                                    > Yahoo! Groups Sponsor
                                    >
                                    > ADVERTISEMENT
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                                    > <l.gif>
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                                    > • To visit your group on the web, go to:
                                    > http://groups.yahoo.com/group/usa-tesla/
                                    >  
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                                    >  
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                                    > Service.
                                    >
                                    >
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