I am working on detecting the amplitude of a signal coming from a guitar pickup. I am using an esp32 and an LM386 module for amplifying the signal.

I get quite stable readings with a multimeter, but the readings on the Arduino IDE show peaks and also peaks come when no signal should be there.

Arduino IDE Readings

Here is a link for short videos of both the esp32 readings and the multimeter:



Simple code:

int ampedVoltagePin = 12;

void setup() {
  pinMode(ampedVoltagePin, INPUT);

void loop() {




1 Answer 1


0.1 Hz is not enough to measure audible frequencies. You need to get at least double the sampling frequency for the signal you measure. See also: https://en.wikipedia.org/wiki/Nyquist_frequency

Say you have 500 Hz, then you need to sample at least 1000 Hz, or 1 ms. Then you can attempt peak detection.


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