Electronics > Projects, Designs, and Technical Stuff
(Solved) Electret Microphone to uC
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kolbep:
Hi All,
Another quick project I am working on,
a (rough idea) dB Meter that logs to Thingspeak, or local server.
My thought is to take a Electret Microphone -> Single Transistor Amplifier -> Esp8266 Analogue Input.
I have used this schematic for inspiration :
I am planning to use a Sonoff (ESP8266) for this, so I can easily pull 3.3v and Ground from it. But the Analogue Input is rated at 1v (for 1024)
But, the amplifier circuit produces a positive/negative wave, which is centred around mid supply. which means when there is very little signal from the Mic (and through the amplifier), the reading from the ADC will be 512.
Meaning (because the + and - swings of the signal are almost equal), I will only really have (1024-512 = 512) resolution.
What I would like to do is : Set the Gain (using the feedback resistor) to a Peak-To-Peak Value of 2V,
then throw away the -ve part of the signal, then shift the lowest part of the signal down to 0v.
Because I am only worried about the Peak really, I do not need to worry too much about the missing bottom half.
That way I will only have a positive signal coming into the uC, ranging from 0v (no signal) to 1v (as loud as it can get) for the full 1024 resolution)
I have tried googling this, but my google-fu is failing me. or almost everybody does not want to throw away half the signal.
Thanks once again for any assistance.
kolbep:
Never Mind,
Just stumbled across a Peak Detector.
That is the term I needed.
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