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Topic: Arduino Peak Detector and Uni-Directional Microphone (Read 1 time) previous topic - next topic


Apr 29, 2019, 05:31 pm Last Edit: Apr 29, 2019, 05:32 pm by VosemGov
Firstly, I have a multi-meter and this device will be in a room with acoustic foam in it. Secondly, I got this from a post over at https://electronics.stackexchange.com/questions/429802/uni-directional-electret-microphones-and-an-arduino/429818?noredirect=1#


Apr 29, 2019, 05:59 pm Last Edit: Apr 29, 2019, 06:00 pm by DVDdoug
The circuit is simply wrong, I a tempted to say go find a proper one, but basically the inverting and non-inverting inputs are swapped over, so the opamp is a comparator with a vast amount of hysteresis.
Good catch!!!  ...I did not notice that.   :smiley-red:

Swap the + &- inputs to the op-amp (so you get negative feedback to control the gain) and increase the feedback resistor R3 for more gain, and it should work.

Or, SparkFun publishes the schematic for their board if you want to see a another version/option.  (You can leave-out the buffer since the Arduino is has a high impedance input, and you can leave-out the Schmitt trigger since you only want an analog output.

I've made amplifiers and I've made peak detectors but I've never made an all-in-one circuit with an electret mic.   ..If it was me, I'd buy the boards.   The cost is going to be about the same and you don't have the hassle of building, testing, and debugging and you get a nicely-assembled printed circuit board without having to design your own board.   (Although, I would prefer a board with a gain-adjustment pot.)   


Thank you very much everyone, and to DVDdoug, I swapped the two inputs and am getting the same results... I think I have probably ruined the circuit somewhere when swapping around connections. The reason I want my own board is so I can have all 9 of these around the outside on one PCB rather then a lot of them on top of each other, which I feel in the long run will make it cheaper. Since I am remaking the whole circuit, should I go with the sparkfun schematic or the one I have listed below? Many Thanks,

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