The source code and Gerber files for the Circuit Notebook article titled "Digitally controlled preamp with tone controls" from the November 2022 issue.

Software updated to v2 on 12/03/2024: "I added a 1000us delay for the conversion time of the ADC. It improved the Boost of bass and treble. Before populating C34 (10uFconnected to RESET), program the ATMEGA328P first via the ICSP port."