OK - I was wrong.
It isn't a straight analog meter.
Quote from the faria instruments datasheet.... who seem to be professional respected providers.
'Tachometers will zero when the key is turned on. It doesn't matter what the tach reads with the key off.'
A straight analog movement would return to zero with it's spring.
So this must be a modern quadrature or pulse counting type movement as described in my earlier post #24, driven by internal electronics.
- either way you can't drive it with PWM from an arduino.
Only with a variable frequency signal of various possible types..
regards
Allan
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