[sdiy] Trying to establish confidence in my test equipment

[Benjamin Riggs]

Ok, most of what everyone is saying is correct (I think) but I'll put my
view on taking measurements. I only have one multimeter, a fluke 179. if I
want acurate measurements I take it to work and do it there (on a calibrated
and NATA certified agilent 3458A DMM) but I've yet to do that. The fact I
only have 1 DMM at home lets my theory here work easily, but the idea is
that if you got a stable reference, it don't matter how accurate it is so
long as that you have a stable reference and you use that as your reference.

Ok a volt is a volt is a volt to as many decimal places as you like, same
with amps and ohm. When I'm doing stuff at home (cause my equipment is not
calibrated), I pretend volts are now apples, my current is oranges and
resistance is apricots. Then I can do my own calculations.

Acording to ohms law, apples = oranges/apricots
Power (appleoranges) = apples*oranges = oranges^2 * apricots = apples^2 /
apricots

I just went and measured the battery in my car with my fluke, 12.87apples
across the terminals.
Hope you get my drift.

On my synths, so long as my tuning is 1 apple per octive, I'm happy. I'm
confident my fluke is within +-5% (of apples = volts) so I know when the
power socket in the wall measures 240 apples AC I shouldn't stick my finger
in it.

So long as the frequency (this is where you may need an acurate instrument)
and scaling (apples/octive) is right, I don't think accuracy of the
apples/oranges/apricots measurement is really important, so long as the
reference to which you calibrated your intrument per measurement units is
stable.

Ben.

Ps. I know drift is important here even though I measure in
apples/oranges/apricots. I've yet to see my fluke drift, my measurements to
date have been repeatable, but then again it's only 4 1/2 digits precision.