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Dual belts?

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  • rmdscuba
    Hi all, I m starting construction on my 3rd (& largest)VDG. I m contemplating running two belts for a higher current (for a later possible project). My
    Message 1 of 7 , Jan 4, 2007
      Hi all,
      I'm starting construction on my 3rd (& largest)VDG.
      I'm contemplating running two belts for a higher current (for a later
      possible project).
      My question is, has anyone seen multiple belt units in operation?
      I was going to have the two faces of the belt closest to each other
      running in the same direction, so as to minimize any charge bleeding
      if they were running in opposite directions.
      Does this make sense?
      Opinions on the belt direction(s)?

      Haven't decided on belt material yet, either Thera-Band or Plasti-dip
      on cloth.

      {parts so far;
      -108VDC motor with a PWM controller via a 100VAC autotransformer,
      rectified/filtered
      -2x14" Ikea globes
      -4" to 4.5"(haven't decided on length yet)x 1.25" dia. brass rollers
      on 3/8" shafts/bearings to fit in 5.75" ID sewer pipe column
      -6.5 kV @ 320 mA charge power pack (from old copier)}

      Thanks in advance!
    • Elmer Wiersma
      I have seen multiple belt unit with something like 6 belts side by side but that was on a professional particle accelerator and so the machine would probably
      Message 2 of 7 , Jan 5, 2007
        I have seen multiple belt unit with something like 6 belts side by side but that was on a professional particle accelerator and so the machine would probably have been hugely expensive. But I think you are right in that the two faces next to each other should run in the same direction because of charges cancelling out and the fact that opposite charges attract each other and in your suggestion the would repel each other which would lower the possible touching of the belts.
         
        Elmer
         
        ----- Original Message -----
        From: rmdscuba
        Sent: Friday, January 05, 2007 4:10 AM
        Subject: [VanDeGraaffGenerator] Dual belts?

        Hi all,
        I'm starting construction on my 3rd (& largest)VDG.
        I'm contemplating running two belts for a higher current (for a later
        possible project).
        My question is, has anyone seen multiple belt units in operation?
        I was going to have the two faces of the belt closest to each other
        running in the same direction, so as to minimize any charge bleeding
        if they were running in opposite directions.
        Does this make sense?
        Opinions on the belt direction(s) ?

        Haven't decided on belt material yet, either Thera-Band or Plasti-dip
        on cloth.

        {parts so far;
        -108VDC motor with a PWM controller via a 100VAC autotransformer,
        rectified/filtered
        -2x14" Ikea globes
        -4" to 4.5"(haven't decided on length yet)x 1.25" dia. brass rollers
        on 3/8" shafts/bearings to fit in 5.75" ID sewer pipe column
        -6.5 kV @ 320 mA charge power pack (from old copier)}

        Thanks in advance!

      • Richard Linder
        Boston Museum of Science has the original (huge) VDG on demo daily. I had a tour of the guts sometime ago and had a chance to take a look at the multiple belt
        Message 3 of 7 , Jan 5, 2007

          Boston Museum of Science has the original (huge) VDG on demo daily. I had a tour of the guts sometime ago and had a chance to take a look at the multiple belt arrangement. I could not stay in the basement room while it was running but inspecting the drive pulleys seem to indicate that all the belts were running symmetrically.

           

          If you have the inner surfaces of the two belts running in the same direction, granted they will oppose each other and not touch. However the opposing forces will assist the belt to bow inward and compound the effect of the two sides of the same belt attracting each other. Of course this is assuming the spacing between the inner sides of the belts is the same as the diameter of the rollers.

           

          It seems to be a worthwhile experiment since reversing belt direction should only require a minimum of mechanical changes.

           

          Dick   

        • Daniel
          Have a look at Fig 3 in http://freepatentsonline.com/1991236.pdf Dont know if it s the best solution, with the belts going in that direction, but would be
          Message 4 of 7 , Jan 12, 2007
            Have a look at Fig 3 in http://freepatentsonline.com/1991236.pdf
            Dont know if it's the best solution, with the belts going in that
            direction, but would be simple to build and adjust.
          • Richard Linder
            I was under the initial impression that you were thinking about two belts in one column. The patent appears to be a single belt in two generators. In that case
            Message 5 of 7 , Jan 13, 2007

              I was under the initial impression that you were thinking about two belts in one column. The patent appears to be a single belt in two generators. In that case you would want the terminals to be charged in opposing polarity.

               

              DL

               


              From: VanDeGraaffGenerator@yahoogroups.com [mailto: VanDeGraaffGenerator@yahoogroups.com ] On Behalf Of Daniel
              Sent: Friday, January 12, 2007 12:35 PM
              To: VanDeGraaffGenerator@yahoogroups.com
              Subject: [VanDeGraaffGenerator] Re: Dual belts?

               

              Have a look at Fig 3 in http://freepatentso nline.com/ 1991236.pdf
              Dont know if it's the best solution, with the belts going in that
              direction, but would be simple to build and adjust.

            • Dan Robinson
              The VDG at Boston s Museum of Science uses a dual-belt system: http://www.mos.org/sln/toe/construction/beltdriveside.jpeg Dan
              Message 6 of 7 , Jan 13, 2007
                The VDG at Boston's Museum of Science uses a dual-belt system:

                http://www.mos.org/sln/toe/construction/beltdriveside.jpeg

                Dan
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              • Daniel
                Fig 3 describes two belts in one column, charging at the same polarity. And it suggests that you make two opposite polarity vdg to have a higher voltage across
                Message 7 of 7 , Jan 17, 2007
                  Fig 3 describes two belts in one column, charging at the same polarity.
                  And it suggests that you make two opposite polarity vdg to have a
                  higher voltage across the two ends.
                  It also describes a more active method to charge and discharge the
                  belt, rather than just having a single comb in the terminal.


                  --- In VanDeGraaffGenerator@yahoogroups.com, "Richard Linder"
                  <linder@...> wrote:
                  >
                  > I was under the initial impression that you were thinking about two
                  belts in
                  > one column. The patent appears to be a single belt in two generators. In
                  > that case you would want the terminals to be charged in opposing
                  polarity.
                  >
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