Jim Yanik wrote:

Robert Baer wrote in
hlink.net:


MassiveProng wrote:

On Mon, 05 Mar 2007 20:27:02 GMT, ehsjr Gave
us:



I don't know what your meter does. I assume it's
like any other. If so, it uses a shunt and develops
a voltage across the shunt so it is the same principle
as what I'm taking about, but not the same values.
AFAIK, they don't use a megohm neighborhood shunt
for low current - but then, I don't have any
meters with an nA scale.



They don't. It is a precision, low value shunt resistor, and they
read voltage across it to determine the current through it.

And that is *exactly* what i proposed with the "trick"; place the DVM
on the 200mVFS scale, add a shunt 1.11Meg resistor (that means in
parallel; use the dictionary) across the meter and the sensitivity of
this network is 200nAFS.
Simple ohms law...



After reading all this,I checked the $3 DMM I bought at a Harbor Freight
sidewalk sale,and it turns out the *input Z is only ONE megohm*. YUK!

I only bought it as a 2nd DMM,for monitoring PS outputs and the like.
The manual did not list that particular spec,either....

I bet it also does not state the input Z onthe current scales, or the
current(s) to be expected on the resistance scales.
OTH, most meter manuals leave out most of those (significant, at
times) details.