Re: Probes for Tek Scope

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

Original poster: "Daniel Barrett by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dbarrett-at-clearcube-dot-com>

    I have had some luck with a current transformer type probe. You can make
one easily and on the cheap if you are willing to put a little work into
callibrating it. The idea is to take a ferrite core and wind, say, 100 turns
of wire on it and connect this to a load resistor and your scope. You then
run the wire on which you are trying to measure the current on through the
center of the torroid. This forms a one turn to 100 turn transformer. The
output of the 100 turn winding (across the load resistor) will be
proportional to the currrent flowing through the wire. At these voltages,
potting the whole thing in epoxy or something would probably be a good idea.
It's also important to select the right ferrite material for the torroid
core. At Tesla coil frequencies, "Material #77" would probably be a good
choice. You can get these cores in small quantities from Amidon Associates.
A good choice to start with might be an FT-82-77 core. It's not pretty, but
it's cheap :) Hope that helps!
db

> current probe, but I figure that I can make one for much less! Does anyone
> havea design for a good current probe that I can have?