Synth In a Box

I have been conducting a series of music electronics workshops in conjunction with Switched On, the awesome Austin synthesizer shop. In the November 2011 workshop we build a new mini synthesizer that I designed.


It is a simple CMOS synth, but it has a lot of features:

  • Two audio oscillators
  • Two LFOs – one per oscillator
  • Pseudo ring modulator effect – the classic CD4011 XNOR circuit
  • Attack/decay volume envelope – the even more classic single transistor VCA
  • Master volume control and separate volume controls for each oscillator and the ring mod
  • Five passive low pass filters for wave shaping of the LFOs, oscillators and ring mod
  • Three modes: constant sound, gated (using the pushbutton) or repeated
  • Repeat circuit with separate controls for on time and off time
  • Built in amplifier and speaker as well as 1/4" output jack

The cardboard box enclosure is a bit of fun. One of the best parts of DIY synth is building the enclosure. I have seen, and built, all sorts of enclosures, but I think this might be the first synth built into the box that the parts come in.

I actually had eight kits leftover from the workshop, but they're all gone now. If you want to build one yourself, just follow the diagrams below. Given that the preceding sentence constitutes the complete build instructions, I would consider this at least an intermediate level project. Of course, if you do want to build one and have any questions, feel free to contact me. I am always happy to help. The below diagrams are also available in this PDF file, which also includes the bill of materials. Oh, and you can use any enclosure - it doesn't have to be cardboard!

Synth In a Box Sample Sounds by Delptronics

Schematic Diagram

Synth Workshop Schematic

Part Placement

Synth Workshop Part Placement

Panel Connections

Synth Workshop Panel Connections