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Re: [beam] Using a polarity sensitive cap...

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  • Pat Nicklas
    Sure that will prevent the cap from blowing up, but I can t tell you if it will work in your circuit or not. What is the circuit your using the cap in? By the
    Message 1 of 10 , Feb 1, 2002
      Sure that will prevent the cap from blowing up, but I can't tell you if it
      will work in your circuit or not. What is the circuit your using the cap
      in?

      By the way, if you are not already aware, what you made with the diodes is a
      full-wave bridge rectifier. By adding the cap, you have effectively created
      the filtering stage of a simple power supply. Not very relevant, but I
      figured I'd point that out :)

      Later,

      Pat


      >From: "Ori" <sbarbut@...>
      >Reply-To: beam@yahoogroups.com
      >To: <beam@yahoogroups.com>
      >Subject: [beam] Using a polarity sensitive cap...
      >Date: Fri, 1 Feb 2002 19:41:47 -0800
      >
      >Hi everyone!
      >
      >I've got a polarity sensitive cap that I need to use without polarity
      >sensitivity... Can I do something like this?
      >
      > Lead 1
      > _____ | _____
      >----| | | -------------|--------------| | |-----
      >| `````````` `````````` |
      >| _____ Cap |
      >|------------------| | |----------------------------|
      >| ````````` |
      >| _____ _____ |
      >----| | | -------------|--------------| | |----
      > `````````` | `````````
      > |
      > Lead 2
      >
      >Is this diagram OK? The thing in the center is the cap, the rest are 1N4148
      >diodes. Thanks,
      >
      >Ori




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    • wrighterpessimist
      Perhaps I m missing something, but why don t you just use a non-polar cap? .001uf seems to be a common enough value that you can just get one at Radio slack.
      Message 2 of 10 , Feb 1, 2002
        Perhaps I'm missing something, but why don't you just use a non-polar
        cap? .001uf seems to be a common enough value that you can just get
        one at Radio slack. Might just save some headaches. <shrug> But if you
        don't have access to any electronics places locally, I understand the
        dilemna.

        Cheers,
        Wrighter

        --- In beam@y..., "Ori" <sbarbut@s...> wrote:
        > It's the 0.001 uF cap in this circuit <
        > http://groups.yahoo.com/group/beam/files/P5v2.gif >... It's the
        lowest cap
        > on the schematic, so it's scrolling time!
        >
        > I bought the cap from BG Micro... I didn't know that it would be
        polarity
        > sensitive!
        >
        > Ori
        >
        > ----- Original Message -----
        > From: "Pat Nicklas" <pn0853@h...>
        > To: <beam@y...>
        > Sent: Friday, February 01, 2002 6:20 PM
        > Subject: Re: [beam] Using a polarity sensitive cap...
        >
        >
        > > Sure that will prevent the cap from blowing up, but I can't tell
        you if it
        > > will work in your circuit or not. What is the circuit your using
        the cap
        > > in?
        > >
        > > By the way, if you are not already aware, what you made with the
        diodes is
        > a
        > > full-wave bridge rectifier. By adding the cap, you have
        effectively
        > created
        > > the filtering stage of a simple power supply. Not very relevant,
        but I
        > > figured I'd point that out :)
        > >
        > > Later,
        > >
        > > Pat
        > >
        > >
        > > >From: "Ori" <sbarbut@s...>
        > > >Reply-To: beam@y...
        > > >To: <beam@y...>
        > > >Subject: [beam] Using a polarity sensitive cap...
        > > >Date: Fri, 1 Feb 2002 19:41:47 -0800
        > > >
        > > >Hi everyone!
        > > >
        > > >I've got a polarity sensitive cap that I need to use without
        polarity
        > > >sensitivity... Can I do something like this?
        > > >
        > > > Lead 1
        > > > _____ | _____
        > > >----| | | -------------|--------------| | |-----
        > > >| `````````` ``````````
        |
        > > >| _____ Cap |
        > > >|------------------| | |----------------------------|
        > > >| `````````
        |
        > > >| _____ _____ |
        > > >----| | | -------------|--------------| | |----
        > > > `````````` | `````````
        > > > |
        > > > Lead 2
        > > >
        > > >Is this diagram OK? The thing in the center is the cap, the rest
        are
        > 1N4148
        > > >diodes. Thanks,
        > > >
        > > >Ori
        > >
        > >
        > >
        > >
        > > _________________________________________________________________
        > > Get your FREE download of MSN Explorer at
        > http://explorer.msn.com/intl.asp.
        > >
        > >
        > >
        > > To unsubscribe from this group, send an email to:
        > > beam-unsubscribe@e...
        > >
        > >
        > >
        > > Your use of Yahoo! Groups is subject to
        http://docs.yahoo.com/info/terms/
        > >
        > >
      • Ori
        Hi everyone! I ve got a polarity sensitive cap that I need to use without polarity sensitivity... Can I do something like this? Lead 1 ... Lead 2 Is this
        Message 3 of 10 , Feb 1, 2002
          Hi everyone!
           
          I've got a polarity sensitive cap that I need to use without polarity sensitivity... Can I do something like this?
           
                                         Lead 1
                 _____                   |                   _____
          ----|         |  | -------------|--------------|        |  |-----
          |     ``````````                                      ``````````     |
          |                         _____   Cap                           |
          |------------------|  |        |----------------------------|
          |                        `````````                                      |
          |     _____                                         _____     |
          ----|         |  | -------------|--------------|        |  |----
                ``````````                  |                   `````````     
                                               |
                                          Lead 2
           
          Is this diagram OK? The thing in the center is the cap, the rest are 1N4148 diodes. Thanks,
           
          Ori
        • dkbovaird@aol.com
          How did you find that it was polarity sensitive? I ve never seen a .001uf cap that was polarized, which doesn t mean they don t exist but I think pretty rare.
          Message 4 of 10 , Feb 1, 2002
            How did you find that it was polarity sensitive? I've never seen a .001uf cap
            that was polarized, which doesn't mean they don't exist but I think pretty
            rare.

            dave.
          • Pat Nicklas
            Sounds very strange. A .001uF cap should be small. I ve also never seen a polarized cap that small, but I suppose it s possible. Looking at the schematic, I
            Message 5 of 10 , Feb 1, 2002
              Sounds very strange. A .001uF cap should be small. I've also never seen a
              polarized cap that small, but I suppose it's possible.

              Looking at the schematic, I can't really tell what the cap is doing. If
              it's a timing cap, you will or course want to use the recommended value. If
              it's just a filter cap, you should be able to use a different value anywhere
              around .001uF. I guess the best person to ask would be the designer--Wilf.

              Radioshack definitely sells .001uF caps. They will be the ceramic type, and
              will cost you three times as much as if you ordered them from a place like
              Digikey. I guess that's the price you pay for convenience :)

              Good luck!

              -PAT


              >From: "Ori" <sbarbut@...>
              >Reply-To: beam@yahoogroups.com
              >To: <beam@yahoogroups.com>
              >Subject: Re: [beam] Using a polarity sensitive cap...
              >Date: Fri, 1 Feb 2002 23:30:46 -0800
              >
              >There's a stripe on one side! It's a dead giveaway... :) It's big, too...
              >about the size of a 20 uF, 100 V cap... So they sell these at radioshack?
              >I'll go, then... When I ordered it, I didn't know!
              >
              >Ori
              >
              >----- Original Message -----
              >From: <dkbovaird@...>
              >To: <beam@yahoogroups.com>
              >Sent: Friday, February 01, 2002 7:47 PM
              >Subject: Re: [beam] Using a polarity sensitive cap...
              >
              >
              > > How did you find that it was polarity sensitive? I've never seen a
              >.001uf
              >cap
              > > that was polarized, which doesn't mean they don't exist but I think
              >pretty
              > > rare.
              > >
              > > dave.
              > >
              > >
              > > To unsubscribe from this group, send an email to:
              > > beam-unsubscribe@egroups.com
              > >
              > >
              > >
              > > Your use of Yahoo! Groups is subject to
              >http://docs.yahoo.com/info/terms/
              > >
              > >
              >




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            • Ori
              It s the 0.001 uF cap in this circuit ... It s the lowest cap on the schematic, so it s scrolling time! I
              Message 6 of 10 , Feb 1, 2002
                It's the 0.001 uF cap in this circuit <
                http://groups.yahoo.com/group/beam/files/P5v2.gif >... It's the lowest cap
                on the schematic, so it's scrolling time!

                I bought the cap from BG Micro... I didn't know that it would be polarity
                sensitive!

                Ori

                ----- Original Message -----
                From: "Pat Nicklas" <pn0853@...>
                To: <beam@yahoogroups.com>
                Sent: Friday, February 01, 2002 6:20 PM
                Subject: Re: [beam] Using a polarity sensitive cap...


                > Sure that will prevent the cap from blowing up, but I can't tell you if it
                > will work in your circuit or not. What is the circuit your using the cap
                > in?
                >
                > By the way, if you are not already aware, what you made with the diodes is
                a
                > full-wave bridge rectifier. By adding the cap, you have effectively
                created
                > the filtering stage of a simple power supply. Not very relevant, but I
                > figured I'd point that out :)
                >
                > Later,
                >
                > Pat
                >
                >
                > >From: "Ori" <sbarbut@...>
                > >Reply-To: beam@yahoogroups.com
                > >To: <beam@yahoogroups.com>
                > >Subject: [beam] Using a polarity sensitive cap...
                > >Date: Fri, 1 Feb 2002 19:41:47 -0800
                > >
                > >Hi everyone!
                > >
                > >I've got a polarity sensitive cap that I need to use without polarity
                > >sensitivity... Can I do something like this?
                > >
                > > Lead 1
                > > _____ | _____
                > >----| | | -------------|--------------| | |-----
                > >| `````````` `````````` |
                > >| _____ Cap |
                > >|------------------| | |----------------------------|
                > >| ````````` |
                > >| _____ _____ |
                > >----| | | -------------|--------------| | |----
                > > `````````` | `````````
                > > |
                > > Lead 2
                > >
                > >Is this diagram OK? The thing in the center is the cap, the rest are
                1N4148
                > >diodes. Thanks,
                > >
                > >Ori
                >
                >
                >
                >
                > _________________________________________________________________
                > Get your FREE download of MSN Explorer at
                http://explorer.msn.com/intl.asp.
                >
                >
                >
                > To unsubscribe from this group, send an email to:
                > beam-unsubscribe@egroups.com
                >
                >
                >
                > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                >
                >
              • Ori
                There s a stripe on one side! It s a dead giveaway... :) It s big, too... about the size of a 20 uF, 100 V cap... So they sell these at radioshack? I ll go,
                Message 7 of 10 , Feb 1, 2002
                  There's a stripe on one side! It's a dead giveaway... :) It's big, too...
                  about the size of a 20 uF, 100 V cap... So they sell these at radioshack?
                  I'll go, then... When I ordered it, I didn't know!

                  Ori

                  ----- Original Message -----
                  From: <dkbovaird@...>
                  To: <beam@yahoogroups.com>
                  Sent: Friday, February 01, 2002 7:47 PM
                  Subject: Re: [beam] Using a polarity sensitive cap...


                  > How did you find that it was polarity sensitive? I've never seen a .001uf
                  cap
                  > that was polarized, which doesn't mean they don't exist but I think pretty
                  > rare.
                  >
                  > dave.
                  >
                  >
                  > To unsubscribe from this group, send an email to:
                  > beam-unsubscribe@egroups.com
                  >
                  >
                  >
                  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                  >
                  >
                • dkbovaird@aol.com
                  wierd...never seen one like that... dave.
                  Message 8 of 10 , Feb 1, 2002
                    wierd...never seen one like that...

                    dave.
                  • Wilf Rigter
                    99.99% of capacitors under 1uF are non-polarized. The 0.001uF is no exception. In that particular application you can leave the cap off although you risk some
                    Message 9 of 10 , Feb 2, 2002
                      99.99% of capacitors under 1uF are non-polarized. The 0.001uF is no
                      exception. In that particular application you can leave the cap off although
                      you risk some hf oscillations depending on the layout of the circuit.
                      Otherwise almost any value cap below 0.01 will be ok too since the frequency
                      will vary depending on light levels.

                      But it useful to know how to make up a large non-polarized cap using
                      electrolytic capacitors. These are commonly used in passive crossover
                      circuits (filters) for speaker systems. They are also used for example in AC
                      motor circuits. Motor starter caps are commercially available up to 300uF
                      and 600V. Attached are typical circuits for making AC caps using common
                      polarized electrolytic caps. The circuit with the diodes is more reliable
                      since the diodes prevent reverse voltage across the caps.

                      Even though very simple, these circuits have their own little secrets: These
                      circuits are related to voltage doubler circuits.
                      the voltage between the caps in the both circuits will be negative with
                      respect to both end terminals and equal to the highest (recent) peak voltage
                      across both caps. The inrush capacitance will be higher initially (double
                      for the diode version) as the capacitors charge up to their equilibrium
                      condition (in as little as one half cycle for the diode version).

                      wilf


                      --- In beam@y..., "Ori" <sbarbut@s...> wrote:
                      > It's the 0.001 uF cap in this circuit <
                      > http://groups.yahoo.com/group/beam/files/P5v2.gif >... It's the
                      > lowest cap
                    • jbsandcs
                      ... Ori, Many non-electrolytic large foil wrapped capacitors are marked with a band at one end. This mark indicates the lead that is connected to the outer
                      Message 10 of 10 , Feb 2, 2002
                        --- In beam@y..., "Ori" <sbarbut@s...> wrote:
                        > Hi everyone!
                        >
                        > I've got a polarity sensitive cap that I need to use without
                        > polarity sensitivity... Can I do something like this?

                        Ori,

                        Many non-electrolytic large foil wrapped capacitors are marked with a
                        band at one end. This mark indicates the lead that is connected to the
                        outer foil wrap. This is important in RF some applications but does
                        not mean that the capacitor has DC polarity sensitivity.

                        Jeff
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