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Electronic Candle Blow out

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The author is Colin Mitchell

Yeah, that's the guy. You know him maybe? :)

On a serious note you are one of very few people anymore to make sure when you post a circuit it is tried and tested. Anymore that unfortunately seems to be the exception rather than the norm and that is really tragic. You also take the love affair with the circuits a step beyond explaining the circuits or more important the operation of the transistor. That being what sets Colin Mitchell's site well above so many of the others making it what it is.

Ron
 
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I simulated the input transistor circuit. Its max gain is about 32dB. In the simulations I changed the scale so that max output is about 0dB.
1) With a 100nF input coupling capacitor almost all of the audible range is passed with -3dB at about 120Hz.
2) With a 10nF input coupling capacitor most voice frequencies are passed with -3dB at about 1200Hz.
3) With a 1nF input coupling capacitor the upper audible range is passed with -3dB at about 15kHz.

I think a "puff" is high audio frequencies. Then i would use a 1nF or 2nf input coupling capacitor so that normal speech, background sounds and music does not trigger the circuit.
 
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