Modular Synth

DIY Modular Synth aka Samohrajka
founder: harvie
depends on:
software license:
hardware license:

Goals of this project:

  • Device should produce danceable-noise (so 8-bit lovers will be able to party all night)
  • Device should be as simple as possible (so everyone can resemble it)
  • All components should be available all around the world
  • All components should be as cheap as possible


I've ordered small strobe from china, so once it arrives i can tune it on 10Hz and synchronize the noise with it. And i believe this can make audience in small darkened room of hackerspace pass to their inner hyperspace (or to photosensitive epilepsy shock).


RC Filters

I've been trying to build two simple RC filters, here are the results:

MIDI controlled synthesizer

Another toy i've made:

Added another oscillator (wannabe CMOScillator AM modulation)

PhotoTransistor Hacks

PhotoTransistor + Remote Controls = Noise Jam

TouchScreen Synthesizer

First prototype - DIY toy hardly inspired by Korg Kaossilator and Monotron…

Simplest Possible CMOS/MOSFET LFO

CMOS oscillators are not capable of generating analogue signal on their output, but the voltage on capacitor of those oscillators is purely analogue. You can see what i've captured using soundcard attached directly to the capacitor of my “CMOScillator”: So we can use MOSFET to amplify the voltage on such capacitor and voila - we have analogue LFO!!! (I've chosed MOSFET because CMOS logic is made from MOSFETs and because current can flow in both directions through the MOSFET, so we can use it to drive another “CMOScillator” directly).

The shape of the LFO signal can be slightly altered to produce sine, saw-up and saw-down functions by replacing CMOScillators resistor by two resistors (or pots) distinguished using two diodes, so you will be able to have different capacitor charging and discharging time.

Simplest Possible VCO

HardTekno DrumLoop generated usin saw-down LFO (4093 + LED across potentiometer) and simplest possible CMOS VCO. + bit of messing with circuit (eg.: Sonic Devastator Redesign as a bonus).

Schematic of simple VCO using CMOS 4046. Note that i am attaching VCO input directly to positive pin of LFO capacitor (instead of voltage-divider shown in picture), so i can drive the VCO using almost-saw signal from 4093 oscillator. Also note that 4046 VCO (thanks to voltage-driven MOSFET/CMOS technology) does not suck almost any current from the LFO capacitor, so it does not detune it (and i do NOT need any external discrete MOSFET transistor to amplify that signal as originaly wanted to do).

Here you can see some signals from VCO (upper graph) and LFO (lower graph) that i've caputred using soundcard and audacity:

  1. triangle wave (LFO capacitor is both charged and discharged through resistor)
  2. saw down (BassDrum / Kick) (LFO capacitor is quickly charged using LED/Diode bypass parallel to resitor)
  3. saw up (LFO capacitor is quickly discharged using LED/Diode bypass parallel to resitor)

Atari Punk Console

Classical DIY toy:



One of lunetta's (simple DIY modular synths based on CMOS ICs):


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