DIY Moog Style Synth

This excellent 3 Oscillator synth housed in a Sanyo Calculator is created by Marcus Dunn, guided by an adapted circuit from Pete McBennett, which is shared below. Using reasonably affordable and commonplace components, the synth offers 3 pulsewidth modulated oscillators, as well as an arpeggiator and a resonant low pass filter. It sounds great! The full details on the build are available on Instructables, as well as some coverage on Hackaday. 

Both of their channels have some great videos on, worth checking out. Here's the original circuit... 

First and foremost, I have to give a massive shout out to Pete McBennett who designed this awesome circuit. When I came across it on YouTube I couldn't believe the sound that he managed to get out of a handful of components. The synth has a MASSIVE sound and really growls with heavy bass through a good speaker.

The synth is a pulse width modulated oscillator, routed through a light-controlled resonant low pass filter. The "growling" oscillator tonality is supplied via a PWM and a awesome high-resonance low pass filter.

The light-control aspect which is controlled through 2 Light dependent resistors (LDR), gives amazing musical expression. The heart of the circuit is 5 op amps (LM358) and also a 2 Hex inverter drone synths via a CD40106 IC. The 2 two adjustable drone oscillators give this synth a total of three oscillators.

The only addition that I included was an additional circuit with a couple of vactrols (LED and LDR facing each other, covered by heatshrink. check this ible on how to make one. This function turns the synth into an arpeggiator type synth and is a tonne of fun to play.

Further watching:

More from Marcus Dunn and Pete McBennett

• VC-01 Voicecrafter: Vocal Synth & Sequencer 09-Oct-26
• Bubblegum: Free Pitch Editor 08-Oct-26
• DestroyFX Buffer Override 08-Oct-26
• Oxygene 50th Anniversary 07-Oct-26
• The Great Debate: Firmware Hacking 07-Oct-26