Re: differential probes

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

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

There are high voltage BNCs around

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Cc: <terry.fritz-at-aei-dot-com>
Sent: Tuesday, July 15, 2003 7:26 AM
Subject: Re: differential probes


 > Original poster: "jimmy hynes by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<chunkyboy86-at-yahoo-dot-com>
 >
 > Hello,
 >
 > The PCB file is on my site
 >
<http://www.hot-streamer-dot-com/chunkyboy86/diffprb.pcb>www.hot-streamer-dot-com/ch
unkyboy86/diffprb.pcb
 >
 > There are also some pictures of it
 >
<http://www.hot-streamer-dot-com/chunkyboy86/diffprb.jpg>www.hot-streamer-dot-com/ch
unkyboy86/diffprb.jpg
 > www.hot-streamer-dot-com/chunkyboy86/diffprb2.pcb
 >
 > Someone should probably check it for errors, and either tell me about it
or
 > fix it and give me the new file.
 >
 > One thing that worries me is the BNC connectors. There could be up to 3600
 > volts across the pins, and it doesn't look like it can take it. Should
both
 > connectors be female, and just plug it into the scope through an
extension?
 > It seems like the only way to do it with two channels
 >
 > I changed the switch slightly, the one I was planning on getting will fit
 > in the circuit board, or it can be connected the way Terry was planning.
If
 > everything looks ok, I'll order some boards and parts tomorrow afternoon.
 >
 >
 > --- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  > Original poster: "jimmy hynes by way of Terry Fritz
 >  > <teslalist-at-qwest-dot-net>" <chunkyboy86-at-yahoo-dot-com>
 >  >
 >  > Hey everyone,
 >  >
 >  > I'll lay it all out tomorrow so you guys can check
 >  > it.
 >  > With the surface mount chips, it is probably better
 >  > to
 >  > skip the prototype and go straight to the PCB,
 >  > agree?
 >  > The PCB has a two day turnaround, so I can probably
 >  > get them built by the end of the week. Who wants to
 >  > try one?
 >  >
 >  >
 >  > --- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  > > Original poster: "Terry Fritz"
 >  > <teslalist-at-qwest-dot-net>
 >  > >
 >  > > Hi Ken,
 >  > >
 >  > > At 09:53 PM 7/13/2003 -0500, you wrote:
 >  > > >On Sun, 13 Jul 2003, Tesla list wrote:
 >  > > >
 >  > > > > Original poster: "Terry Fritz"
 >  > > <teslalist-at-qwest-dot-net>
 >  > > > >
 >  > > > > Hi Jimmy, Finn, and All,
 >  > > > >
 >  > > > > This is the present schematic and parts list
 >  > I
 >  > > have in mind for the
 >  > > > > differential probe. I have NOT assembled or
 >  > > tested it yet!
 >  > > > >
 >  > > > > http://hot-streamer-dot-com/temp/DiffProbe-5.gif
 >  > > > >
 >  > > > > http://hot-streamer-dot-com/temp/DiffProbe-5p.gif
 >  > > > >
 >  > > > > It is still just using the basic 150MHz TI
 >  > > THS4151ID differential
 >  > > > > amplifier IC and other straight forward
 >  > parts.
 >  > > > >
 >  > > > > One thing I am "trying" to add is a front end
 >  > > that can take a hard hit. I
 >  > > > > will have a system ground stud and MOVs at
 >  > 1800
 >  > > volts each. These will be!
 >  > > > > fused with low current but high voltage
 >  > fuses.
 >  > > The idea is if you get a
 >  > > > > say 20,000 volt cap on the input, the MOVs
 >  > will
 >  > > clamp it and the fuses will
 >  > > >
 >  > > >How about some neon lamps or one of those glass
 >  > or
 >  > > ceramic tubes the size
 >  > > >of a pencil eraser with metal leads? Both should
 >  > > have a low capacitance,
 >  > > >and don't conduct until 70 volts or so for neon,
 >  > > and several thousand for
 >  > > >the larger ones. Maybe put them both in
 >  > parallel.
 >  > > You probably want the
 >  > > >lowest possible impedance in a short mode,
 >  > > otherwise the probe or what's
 >  > > >left of it will dissipate lots of heat, which
 >  > leads
 >  > > to it blowing up or
 >  > > >catching on fire. Large energy storage caps are
 >  > >! designed this way- to
 >  > > >short out with the lowest impedance so their
 >  > energy
 >  > > is dissipated outside
 >  > > >the cap tank in bussbar and fuses, not inside
 >  > where
 >  > > the tank will build up
 >  > > >pressure and rupture. MOVs are basically
 >  > > firestarting kits.
 >  > > >
 >  > > >KEN
 >  > >
 >  > >
 >  > > I have a "bunch" of Victoreen SGCA-2500D spark
 >  > gaps:
 >  > >
 >  > > http://hot-streamer-dot-com/temp/P7130038.jpg
 >  > >
 >  > > The 2500 volt firing voltage is sort of high.
 >  > But
 >  > > not a big deal here if I
 >  > > put them in parallel with the MOVs... I am
 >  > hoping
 >  > > the "fuses" will break
 >  > > the current before any fires start...
 >  > >
 >  > > Jim also mentions the Sidactors. I think I
 >  > remember
 >  > > of few of them blowing
 >  > > up in my ! face in the early 90'S :o)) But they
 >  > are
 >  > > also another great
 >  > > possibility in this case!!
 >  > >
 >  > > Cheers,
 >  > >
 >  > > Terry
 >  > >
 >  > >
 >  > >
 >  >
 >  >
 >  > =====
 >  > Jimmy
 >  >

 >
 >
 > Jimmy
 >