9 Voice Simple City Drone: is a bank of square wave oscillators with one audio out and mute switches for each channel. It uses a modified S9018 Bipolar Transistor to create a pitch-adjustable square wave.

I designed this board to achieve a sound somewhere between a 3 voice chord, an orchestrated swarm and just droning noise (see video for audio demo).

Each voice has an LED that modulates in time wit the oscillator. The mute switches for each voice allow the user to use as many of the voices as needed.

**NOTE ON CAPACITORS: Each channel has a suggested capacitor value but these can be adjusted and played with for different sounds. A higher value will give a lower range of sound (i.e. a 10uf capacitor will give a much higher pitch than a 100uf capacitor). Going too high will just sound like clicking (sort of like an lfo). I suggest picking a capacitor somewhere between 100uf and 1uf.

Runs on a 9volt battery or external 9volt DC power supply.

This listing comes with the 9 modified transistors. All other components will have to be sourced by buyer. All components will need to be soldered onto the board.

Board comes 62mm*119mm with accompanying transistors. Resistors, capacitors, led, switches, potentiometers and 1/8” audio jack NOT INCLUDED.