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Whistle Switch
by Mike Ellis, 1999, All Rights Reserved

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The whistle switch allows you to turn on, or off, an appliance by whistling at it. I originally built the whistle switch in 1974. Do not attempt to duplicate it from the schematic below, but instead, understand the functions and duplicate these functions with more modern components.

 

               

The audio amp, after the microphone, should have enough gain to produce square waves from input noise. The LC tuned circuit can be replaced by an active bandpass filter, at the frequency that you whistle the easiest. The detector has a slow attach, fast decay, which means that you must whistle solidly for 5 seconds, without interruption. Athough not shown, the J-K flip-flop has a ground pin connected to ground. A zero-crossing detector should be used on the final TRIAC to avoid AM radio hash.

Download the Orcad Schematic File

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