Re: whimshurst--RESEND (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 22 Jul 2003 16:10:39 -0500
From: Ralph Zekelman <hyperion@xxxxxxxxxxxxxx>
To: hvlist@xxxxxxxxxx
Subject: Re: whimshurst--RESEND


  ----- Original Message -----
  From: Ralph Zekelman
  To: hvlist@xxxxxxxxxx
  Sent: Monday, July 21, 2003 7:01 PM
  Subject: whimshurst


  ----- Original Message -----
  From: "High Voltage list" <hvlist@xxxxxxxxxx>
  To: <hvlist@xxxxxxxxxx>
  Sent: Monday, July 21, 2003 8:45 AM
  Subject: wimshurst (fwd)


  > Original poster: Steven Roys <sroys@xxxxxxxx>
  >
  Hi John,

  Back in high school physics (c.1947) there was a huge William
  Welch Wimshurst. The glass disks were at least 16 inches across and driven
  in their opposite directions by a sewing machine belt driven from a crank
  handle. The aluminum segments, cemented to the glass, were brushed at four
  points on each side by rigid rods
  that contacted the plates at 90 degree angles. The brushes were like
  aluminum or tin foil tinsel. Two large Leyden jars held the charge but a
  small knife switch could short the jars so the spark
  came from the charges not stored. The best thing we did was to hold a piece
  of thin plate glass between the electrodes at a minimum distance of spacing.
  Probably a little dangerous but what did  we know. We got an excellent
  demonstration of dielectric strength and capacitance.

  I have always wanted to build one, perhaps out of plastic, but I think I
  would be willing to let some glass shop cut the discs. I guess the most
  difficult part is the arrangement of the hubs. Good luck on your project and
  I would like to hear more about it.

  Ralph Zekelman