Overspeed indicator

Posted on Feb 24, 2013

An op-amp comparator is used to compare the converter output with a dc threshold voltage. The circuit flashes the LED when the input frequency exceeds 100 Hz. Increases in frequency raise the average current out of terminal 3 so that frequencies above 100 Hz reduce the charge time of C2, increasing the LED flashing rate

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IC = LM2907 or LM2917.

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Fernando Jan 11, 2019

Thanks for the diagram. What kind of change have to do it to have the led always on with any input frecuency higher than zero ?

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