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In Reply to: RE: My meter is scaled to 200 ma. posted by Triode_Kingdom on June 19, 2017 at 07:08:19
I have a ton of old panel meters. Most labeled "mA" that have a low scale (500mA or less) are 200mV DC meters without an internal shunt.
Amp meters that are above that always have an external shunt. Far cheaper to test than to assume. :-)
"Most labeled "mA" that have a low scale (500mA or less) are 200mV DC meters without an internal shunt."
If I understand, you're saying the meters are mostly 0.2V FS, and it's the difference in coil resistance that provides different FS current readings. That would mean a 200mA DC panel meter is likely to have a coil resistance of one ohm. Is that correct?
Buy Chinese. Bury freedom.
Most old panel meters need an external resistor network to function correctly. My advice is to test it carefully before putting it in a circuit and destroying it. But yes, if the coil resistance is 1 ohm then it could be used directly as a low current ammeter.
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