Today let’s take a look at a vintage 1962 soviet era vibrating reed frequency meter. It’s an analog frequency meter based on multiple metal strips (reeds). Each of them has a slightly different mechanical resonant frequency. It also contains a coil connected to an AC current. The reed with a resonant frequency very close to the frequency of the current in the coil will vibrate. This will indicate the frequency on the scale. Those devices have a narrow range of measured frequencies. They are mostly used to measure the frequency of a 50Hz, 60Hz or 400Hz mains.
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