Re: HV probe for primary measurements

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

Original poster: "Daniel Barrett by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dbarrett1-at-austin.rr-dot-com>

> > Can I just use a big string of resistors? The idea of directly
> > measuring the primary voltages and currents, quite frankly, scares
> > the utter crap out of me. But I am determined to investigate them. I
> > will NOT be touching the CRO during operation as a result. I just
> > don't want to go anywhere near it.
> > Cheers,
> > Greg.

    I'm also scared schick-less of frying expensive test gear- One thing
I've had good luck with to reasure myself that I'm not about to do something
expensive:

    Connect your new homegrown HV / HA probe to a little perf board which
has an op-amp like a TL072. Run your coil for a while. If the op-amp still
lives when you are done, your probe probably won't kill your $4k scope.
TL072's are cheap and fairly easy to fry, and it takes 10 minutes to build a
little amp board (put the opamp in a socket to you can re-use  the board
should you discover your probe "need more work"...
$.02
db