IN-13 bargraph audio visualizer

DIY audio spectrum analyzer with IN-13 bargraph tubes.
- 10 bands (31 Hz - 16 kHz)
- line input/output
- built-in microphone
- adjustable PWM-controlled "release" time (1:40 3:00)
- op-amp based circuitry

Original schematic that I made for myself during the project:
https://1drv.ms/u/s!AvJDG4IatLAxhNR46buD2xrnipsbrw?e=XWBl1X
It's pretty hard to read (just a sketch) and doesn't have everything needed (for example you need to calculate the band-pass filter components for each frequency band, I used Q=1.5 filter which works for this 10 band display).

Видео IN-13 bargraph audio visualizer канала jatimat1c