Myles Lazarus

Voice Modulator

Summary

A small battery-powered & rechargeable voice modulator empowered with an ESP32 that allows for custom digital filter implementation with a low-cost, analog input and output stage.

I had been struggling with this project for a long time on how to best implement the filtering, and finally decided on digital filtering due to its robustness and ability to customize the sound much easier than with analog filtering.

gray concrete wall inside building
gray concrete wall inside building
Breadboard

I started with a breadboard mockup of the implementation to test out the capabilities of a tetrenet microphone through a simple BJT amplifier. I also tested the ESP32 DAC output through a class D amplifier IC to validate that what I wanted to do would sound alright and not have any insane distortion from the beginning.

white and black abstract painting
white and black abstract painting
Prototype 1

There was bound to be some mistakes in the first prototype. But the plan is to always find all of the bugs by doing whatever it takes to do a full end-to-end test with what you've got

Fixes

  • Had to lift the LDO enable pin

  • Do not use JTAG pins to program since the ESP32 has a built-in debugger

worm's-eye view photography of concrete building
worm's-eye view photography of concrete building