[Tristar500]

I'm looking to add this new old stock ampere meter to my Chinese laser so I can monitor the current going to the laser tube, I hooked it up in the same way as I've seen in other videos but the meter spikes when just testing with a small pulse from the machine. It says on the meter face to use and external resistor , -f.s,=1MA.

Not sure exactly what this means.

Thanks in advance everybody!

[Sam_Beckham]

External resistor makes me think it's made to use with a shunt. If that's the case it's really reading mV across the shunt(resistor) and not directly measuring current.

[Bdrangdo]

The initials "FS" refer to the full scale movement of the meter which in this case is 1 milliampere. You could try measuring the resistance across the meter and work out what the shunt resistor should be, so to give an indicated full scale movement of 50 milliamperes you would need a shunt resistor with 1/50th of the meters internal resistance. For example if the meter resistance is 500 ohms then use a 10 ohm shunt resistor. I know that is not exactly correct but it will get you in the ball park. Dave

[CitizenOfDreams]

to give an indicated full scale movement of 50 milliamperes you would need a shunt resistor with 1/50th of the meters internal resistance.

1/49th to be exact.