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Old 01-12-22, 11:42 AM
Road Fan
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Location: Ann Arbor, MI
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Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

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I agree with a lot of what has been said here. One thing that I think is needed is to emphasize that if you only want to check that the generator is functioning, the VOM needle movement will show that it is really producing voltage, even if the wheel speed is not steady. If you can spin the wheel steadily you should get an AC signal which will look steady on the VOM. Because the meter is mechanical, its response is far slower than for an electronic AC voltmeter. If you look at the signal with an oscilloscope, it should look like a clean sine wave or one with some kind of distortion or spiking at the peaks, due to magnetic hysteresis and saturation. If there's too much weirdness the generator might be no good, or have the magnets out of place in ways that might be hard to understand without a good set of blueprints or CAD.
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