multimeter conversion

[palito]

Is it possible to convert an analog meter that measures up to 500mA to read
up to 1 amp and also 1.5 amps.

This is to measure the draw on a 12 volt DC circuit. Motor is supposed to
draw 0.91A

Thanks,
Pat

 

[CWatters]

Is it possible to convert an analog meter that measures up to 500mA to read
up to 1 amp and also 1.5 amps.

This is to measure the draw on a 12 volt DC circuit. Motor is supposed to
draw 0.91A

Yes. You need a "shunt".

This is in effect a low value resistor that goes between the terminals of
the meter. In effect it shunts (diverts) some of the current "around" rather
than through the meter. If you had a shunt that diverted 50% of the current
it would read 0-1A.

How they work...
http://www1.jaycar.com.au/images_uploaded/shuntmul.pdf

 

[[email protected]]

To use a shunt:
run the current through the shunt and measure the VOLTS across the
shunt

the shunt must have very low resistance and the voltage reading will
be very low -- millivolts or microvolts. You can calculate the
current, or you can go to the trouble of labeling the meter movement
with a scale to read directly in amps.

You need to get your hands on a shunt, which can be bought from supply
houses on the internet.

Of course, it would be easier just to get a multimeter that includes an
ammeter range
that's high enough for the measurement you want to make. You can get
multimeters with 10 amp range for less than 20 bucks.