So I made an audio level detector with an electret mic fed into an lm386 amplifier which fed into an lm339 comparator to act as switch when an audio threshold was met. This worked well but I'm convinced I can make the circuit much smaller now by utilizing just 2 bjt's but I'm not sure. This is my idea but I could use some input.
The electret mic requires the DC source and outputs only a small voltage and not enough current to turn on a bjt so I was thinking that I could use the first bjt as an amplifier to supply enough current to drive a second bjt into saturation or switching function.
Since I can only get like 5mV out of the electret mic I would have to bias the base of the first transistor by 1 volt or so DC + the output of the electret mic. I could then take this output signal and put a DC blocking cap to allow only the ac to pass to the next transistor and attenuate it as necessary to create a threshold reference which turns on the bjt when this loudness is reached.
Now thinking about it this might make the first bjt unnecessary. Does this circuit sound like it would work? Input appreciated thanks.
The electret mic requires the DC source and outputs only a small voltage and not enough current to turn on a bjt so I was thinking that I could use the first bjt as an amplifier to supply enough current to drive a second bjt into saturation or switching function.
Since I can only get like 5mV out of the electret mic I would have to bias the base of the first transistor by 1 volt or so DC + the output of the electret mic. I could then take this output signal and put a DC blocking cap to allow only the ac to pass to the next transistor and attenuate it as necessary to create a threshold reference which turns on the bjt when this loudness is reached.
Now thinking about it this might make the first bjt unnecessary. Does this circuit sound like it would work? Input appreciated thanks.