mike wrote in :

Sam Goldwasser wrote:
See: http://repairfaq.ece.drexel.edu/sam/hvprobe.htm

Building a voltage divider out of 10, 10M ohm resistors (and suitable
math!) is sufficient and safe.

And if that's what he'd proposed, I probably wouldn't have chimed in
at all. Reread the original post. He said "10 'one meg' resistors in
series". I maintain that the value is too low.

I agree,and it WILL load the HV circuit.Even a 100 Mohm probe does.
I used 4 22.5Mohm or 9 10Mohm 1/2w precision metal film resistors in series
for a simple probe for a 10 Mohm input Z DMM. It works great.


HV ------[90meg]------[DMM 10meg]-----/gnd

If you do the true divider way,you have to compensate for the DMM input
Z,if you want the probe to be reasonably accurate.

--
Jim Yanik
jyanik-at-kua.net