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post #21 of Old 11-15-2012
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Re: Voltage tester idea

Let's see, E over I equals R, yes? So


and the meter draws 0.0000012 amps, 12 millionths of an amp?

and the folks at say:

Voltage drop: 0.0051
Voltage drop percentage: 0.043%
Voltage at the end: 11.9949

Not too bad! I suppose instrument rounding and errors might mean it could show 11.9 instead of 12.0 but from a hundred miles away...(VBG)

OTOH, having seen the way my "good" meters of various ages disagreed (by .2 volts) and the way a HF special couldn't meet it's own specs, I put zero faith (actually, 0.000000000 faith) in meters that have no specs at all, like those specials at dx. Which is why I finally decided to get out the soldering gun and put a 10.00 volt precision reference source in a mini Altoids tin, so there's no guessing, and I *know* when my meters are fibbing. The reference source is good beyond 4 digits, so when I hook it to a meter the meter had damn well say 10.00 or it gets re-educated, as the Chinese would say.
I'll be interested to see how the meters HOLD calibration, now that I've got a way to check on them.
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