Modular Synth

Six Circuits. One Tiny Synth Lab.

Overview

This modular synth is built from six simple circuits: an oscillator, sequencer, VCO, modulator, amplifier, and power distribution board. Together, they form a small experimental system designed to make synthesis and electronics approachable.

The power distribution board lets everything run from a single 9V battery or power supply, with reverse-polarity protection and regulated distribution to each circuit. The goal isn’t to build a perfect Eurorack system, but to make your first sounds and learn the basics of synthesis and electronics without overcomplicating things.

Hex Oscillator

Six independent oscillators packed into a single circuit, built around the classic CD40106. The red PCB identifies it as one of the kit’s waveform-generating circuits. Each oscillator can be used on its own for drones, tones, and simple melodies, or combined with switches to create a six-note polyphonic instrument. Its outputs can also be used as clock sources to synchronize other modules and trigger the sequencer.

One of the most versatile circuits in the kit, it can be an instrument, a drone generator, or the clock at the center of the whole system.

Decade Sequencer

Based around the classic CD4017 decade counter, the Decade Sequencer provides 10 sequential steps for building repeating patterns. Connect 10 potentiometers to its outputs and you have a simple yet powerful sequencer with individual control over each step. Use switches to configure the reset point, mute individual notes, or create shorter sequences.

It can also accept different clock sources, making it easy to integrate with other modules and machines. Just make sure the clock and sequencer are running at compatible voltages.

Dual VCO

It’s up to you. Use one VCO or build two, the PCB has enough room for both. Feed it a control voltage from the Decade Sequencer or any other source, and you’ve got a sound generator.

The VCO can be tweaked to tune it as musically as possible, and its output can then be fed into a waveshaper or filter to smooth out the square wave and shape the sound.

My Small Amp

One of the first projects I built, this versatile little amplifier is incredibly simple. Based around the classic LM386, it can deliver up to around 1W of output power.

It’s perfect for listening to your projects and experiments, and can even be used with a guitar.

Power Distribution Board

A simple way to distribute power to all your boards from one clean power source. It features reverse-polarity protection on the input and can run from a 9V battery or power supply.

With eight flexible outputs, you can connect terminal blocks, JST connectors, or wires directly to the board. A simple utility board that keeps your whole setup powered and organized.