February 7, 2020

Building A Triple Oscillator

By nature all instruments make some sort of noise. Without an oscillation there can be no music, which is why my first eurorack module is a triple oscillator. This design uses transistors in reverse avalanche mode to generate a sawtooth wave. Three separate transistors generate 3 sawtooth waves that are mixed by three 100K ohm resistors. Generation of 3 musical notes allows me to create chords simply by varying the position of the three uppermost knobs. A 4th knob controls tone. The 3.5mm Jack on top is a control voltage (CV) input to adjust the frequency of all three oscillators at once. The jack on the bottom is the output.

Front panel of a Triple Oscillator module
Triple Oscillator module 0001

The original design is from Look Mum No Computer, thanks! I added the tone control a custom CV circuit. As for the metal panel holding everything together, it’s a remnant of my first Windows XP machine from 2007. It’s cut out with an angle grinder, and sanded to the metallic finish on a Delta belt sander I bought for $30 at a yard sale.

Triple Oscillator Layout Drawing
Triple Oscillator Layout Drawing. Print the .pdf to use as a template for cutting and drilling.