Re: differential probes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

On 16 Jul 2003, at 6:33, Tesla list wrote:

 > Original poster: "Daniel Barrett by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <dbarrett1-at-austin.rr-dot-com>
 >
 >      Hi All!
 >      Just a thought here- This spark gap section could really just be 
part of
 > the PC layout: Route the potentially high current signals with maybe 10 mil
 > tracks, separated from each other by an inch, but "T" off a spark gap
 > between these tracks. That way an arc will occur in a controlled spot on the
 > board and the feeding traces will be small enough to vaporise. Should
 > provide an easy to make fuse, but I guess the board would need a lot of
 > rework between accidents ;)
 > db

The problem I see with that (and I've seen it numerous times in
equipment servicing) is that the arc will continue, carbonizing the
board material which might well render the board throwaway material.

Malcolm

 > ----- Original Message -----
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > To: <tesla-at-pupman-dot-com>
 > Sent: Tuesday, July 15, 2003 10:54 PM
 > Subject: RE: differential probes
 >
 >
 >  > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >  >
 >  > Hi Jimmy,
 >  >
 >  > I have the 'stuff' here to find the "precise 0.177 caliber BB 
spacing" but
 >  > ran out of time tonight :-(
 >  >
 >  > I am thinking you should not order any boards till we can work some of
 >  > these details out more.  Today, I talked to some folks that had some
 > strong
 >  > arguments for using cap in parallel with the resistors.  I fear that
 >  > ordering boards now would mean that they would be "obsoleted" pretty
 >  > quickly...  I don't know how much the boards cost, but I would not want
 > you
 >  > spending and serious money on something we know is going to change...
 >  >
 >  > So, I think there are too many question to go getting boards right now.
 > We
 >  > need to work more on this front end fusing and capacitance stuff.  I 
think
 >  > I can get this stuff answered in a few days, so we would have a good
 > chance
 >  > that "that" version would be "the" version.
 >  >
 >  > Cheers,
 >  >
 >  >          Terry
 >  >
 >  >
 >  > At 08:41 PM 7/15/2003 -0700, you wrote:
 >  > >Hi,
 >  > >
 >  > >My stun gun used two staples for a spark gap. They
 >  > >formed an X shape, and could be adjusted by pushing on
 >  > >it. I would just need a way to calibrate it. If I used
 >  > >"BBs" or 0.25 inch balls, I could solder them in
 >  > >holes, and just look up the breakdown voltage for
 >  > >spheres.
 >  > >
 >  > >I'll cut the boards up wherever it looks like it needs
 >  > >it.
 >  > >
 >  > >
 >  > >--- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  > > > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >  > > >
 >  > > > Hi Malcolm,
 >  > > >
 >  > > >
 >  > > > >I haven't downloaded the file as I don't have a
 >  > > > suitable program to
 >  > > > >open it with available on the NW. I do have a tip
 >  > > > to deal with the
 >  > > > >problem mentioned in the previous paragraph: the
 >  > > > way to increase the
 >  > > > >isolation barrier without consuming a lot of board
 >  > > > space is to
 >  > > > >physically cut a slot in the board across the
 >  > > > isolation barrier. This
 >  > > > >gets rid of the problem of surface tracking. I
 >  > > > presume fibreglass is
 >  > > > >the material of choice for this board? <paxolin or
 >  > > > anything like it
 >  > > > >is OUT>.
 >  > > > >
 >  > > > >Malcolm
 >  > > > ><snip>
 >  > > >
 >  > > >
 >  > > > That is a very good idea!  Tracking under these long
 >  > > > resistors could be a
 >  > > > big problem especially with a little left over flux.
 >  > > >
 >  > > > Jimmy - Could we drill 4 big holes under the
 >  > > > resistors?
 >  > > >
 >  > > > Also, I think hooking to the board with very thin
 >  > > > wire and then having
 >  > > > spark gaps on the board to take "bad" events is the
 >  > > > way to go.  Maybe
 >  > > > solder "BB's" or 1/4 inch balls to the board at some
 >  > > > spacing.  The spark
 >  > > > gaps could take a big high voltage high current hit
 >  > > > (arc at 2500V) and then
 >  > > > the thin wires could blow apart and basically take
 >  > > > things out of the
 >  > > > circuit.  I'll see if I can figure something simple
 >  > > > out there...
 >  > > >
 >  > > > Cheers,
 >  > > >
 >  > > >          Terry
 >  > > >
 >  > > >
 >  > > >
 >  > >
 >  > >
 >  > >=====
 >  > >Jimmy
 >  > >
 >
 >
 >