Excellent tip. Very handy use of your Volt Meter module. Thanks for the tip and for the module update!honki-bobo wrote: ↑Thu Nov 11, 2021 7:42 am The ESP-20 Processor module features "Freq -> Volt" conversion. It is not 100% accurate and it doesn't really work below G1 (~49 Hz), but it will get you in the ball park and you can fine tune by ear from there.