Calibrate the Amp meter

Hi Guys
I have attached mA amp meter to my 80w laser and want to make sure the reading is correct when using the laser.
Can I use a multimeter and touch one lead to one terminal of the Amp meter and the other lead to the other terminal to see what the amps are while the laser is busy doing a job?

Would this give me the correct amps and then I can adjust pod on the amp meter?


No. You would get a reading but it wouldn’t be correct. You would have to know the internal resistance of the both the dmm and analog meter and the voltage. Then you could do some math to figure it out.

Generally just set the analog ma meter to 0 when everything is off and that should be good enough.

If you wanted to be more precise then you would need to send the dmm off to be calibrated. Then you could use only the dmm to measure the current with the wires running to the dmm only.

Without knowing that one meter is calibrated correctly then you are just playing a guessing game.

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If you have to, hook mA meters in series, not parallel. In other words, disconnect one wire and out the multi meter in between the installed meter and the laser tube. I have a pair of binding posts with a shorting wire for just this purpose. I want the analog for day to day operations as it reacts quicker. But when I do my power testing twice yearly, I want the digital accuracy. Pull the shorting wire and connect the digital meter and I’m all set for power testing.

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