“This spectrum analyser with 10 channels uses an analog back-end to analyse the incoming signal from line-in or microphone. Acrylic display.
The analogue back end of this 10 channel spectrum analyzer uses 10 band pass filters to divide the input signal into 10 frequency bands
You can connect your audio signal by using the audio input or you can use the microphone input to connect a small condenser microphone. Although using the microphone will limit the frequency response because of its limitations.
The input sensitivity can by adjusted just like brightness and peak hold time. When it does not receive any input signal, after a while, it will go to fire mode in which some leds/display will light up like a fire.
The PCB can be purchased at my Tindie web shop. The firmware (Arduino Sketch ) is open source and you can modify it to your needs.”