Thanks guys
If I have a circuit lets say 1.5 volt bat and a 1.5 volt lamp and I want to
measure the current I would put the meter parallel to a shunt resistor in
the circuit right. But does the shunt resistor not cut down on the voltage
to the lamp
Yes, by 0.05 volts.
But don't just slap a shunt in there and expect to get accurate readings.
Either give yourself a way of trimming it while live, or actually
determine the internal resistance of the meter. Take your setup with
the batt. and series R, adjust it for full-scale, as you've done, and
then take another pot, put it in parallel with the meter (so the meter
and new pot are now in parallel with each other, and that combination
is in series with the B and R), and adjust it until the meter reads
half-scale.
But this will only work if the meter actually _has_ a Zero indication.
Did you meant to say that your meter face has "1" at the very leftmost
spot? If so, you might have to do some more experiments to find out
exactly what this meter is expecting - usually, when there's a meter
that doesn't start at 0, it's used with some kind of custom circuit to
get that offset.
Of course, the other thing (depending on how much headroom you have)
is to turn the meter into a voltmeter, by just adding a series resistor,
and measuring the voltage across the shunt. Doing that gets your
calibration up out of the mud.
Good Luck!
Rich