This got my interest up. Poked around a bit. You can calculate frequency using a true RMS meter. Since most alternating current sources are not a clean, pure sine wave, straight RMS calculations will not work. Or at least would not be very accurate. That’s why true RMS methods are used. Also, the sample window must be short and defined or the frame needs to be short enough so that voltage changes cannot corrupt the calculation - a constant, stable peak to peak amplitude is essential.
I suspect that the generic DMM versions of "tachs" are adequate, but not entirely accurate. I could be wrong, but if you're looking for precision, a dedicated instrument would be the route to take.
I spent some time (decades) in an engineering lab, but mostly slinging code.
Last edited by desertrefugee
on Sat Jul 27, 2019 5:43 pm, edited 1 time in total.
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