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Project Modular Synth
Pino synth 2017-09-20.jpg
A do-it-myself modular synthesizer
Status In progress
Contact pinoaffe
Last Update 2018-03-11

I am currently redoing my case, will probably scrap most if not all modules i made so far, will (try to) do shit properly this time over.

I found some threaded strips at reichelt, and am making a new, lasercut case outta 5mm plywood.



  • close to 4U: 180 mm in height
  • module width will be x*5.08mm, this is a semi-standardized unit "hp"
  • Instead of the 2.7mm front panels i planned on using before, i'll move to 5mm wood.
  • The cases will be in slightly less than 19 inch format
  • standard pot knobs are ....... mm in height


  • CV and audio both on banana jacks
  • front panels and pot knobs will be made from 2.7mm or 5mm plywood using a lasercutter
  • front panel design will incorporate icons, arrows and curves to signify what knob/plug does what

Voltages and Power Supply

  • use desktop power supply, optionally decased?
  • 5
  • 12
  • -12
  • Previously, I made a power bus out of bare copper wire with 3 connections (intended for gnd, +5 and +15 v)
  • This was a pain to work with, so i'll probably use the same threaded strips I use for mounting the modules as power bars
  • these strips are available at reichelt

Working Modules

  • Attenuator
  • CV-Source
  • Signal Copier
  • Signal Selector
  • Buttons
  • Arduino stepped oscillator
  • Speaker
  • Amplifier

Not-working modules

  • Sequencer (currently troubleshooting it)

Presumably Working Modules

  • Auduino 2

Work in progress Modules

  • Clock/Frequency Divider
  • LFO
  • Auduino 1
  • Auduino 3
  • Atari Punk Console

Modules i'll make soon

  • VCO
  • Arduino VCO

Plans for a diy modular synth

Here is the current version of the plans I've been working with. I wrote em for myself, so they might not be very useful for others.





  • 555-based

Stepped Tone Generator

Atari Punk Console

Amplification and Deamplification


  • opamps?


  • VC?


  • 4017 and opamps
  • Dual or triple channel
  • Add a lfo for clock, allow one of the channels to be used as an input for the lfo clock allowing for configureable step length
  • blue pill, step length, direction, ping-pong, multi/single gate, normal length,

Function Generator

Clock Subdivider:

  • 4017

Frequency Subdivider:

  • 4017
  • max clock frequency = 2mhz @5volt, 6mhz @15volt

Clock Multiplier

  • 4046

What you need is a Phase Locked Loop. There is a 4046 CMOS IC that implements one, but you also need a digital divider so you could build a phase comparator and use a synthesizer VCO. The principle is to divide the VCO output down by the ratio you want and then compare the phase with your input signal. The phase comparator produces a CV that makes the VCO track the input frequency at a multiple set by the divider. The simplest is an XOR gate followed by an RC filter, but there are better more sophisticated circuits. The 4046 has two alternatives.

CD4046 application report

Or just Google "Phase Locked Loop"...

Frequency Multiplier

See "Clock Multiplier", but with a higher frequency




Envelope Follower:

  • a basic ac-dc converter, outputs the dc voltage of the peak (the amplitude) when given an ac waveform


cap and inductor

Notch Filter

Low-Pass Filter

  • most popular in modular synths
  • passes low frequency content
  • moog's version: ladder filter

High-Pass Filter

  • passes high frequency content

Band-Pass Filter

All-Pass Filter

  • can be seen as a phase shifter
  • changes phase based on frequency
  • popular sound on guitars
  • when summed with input signal, the frequency-parts that are 180 degrees changed will negate eachother

Moog Ladder Filter















Chord Maker:


  • cv-adder (with maybe an internal VCO)
  • or frequency multiplier and divider, optionally combined with external or internal waveform changer

Could turn into a modulator when CV-ed and supplied with either the output of an LFO (probably quantized)

or the output of a sequencer (also probably quantized)


  • Basically a Chord Maker with a changing interval
  • Could also have an option to switch different inputs to an output rapidly
  • External clock?
  • Decade counter?
  • either:
    • cv-adder (with maybe an internal VCO)
    • or frequency multiplier and divider, optionally combined with external or internal waveform changer


Waveform Changer

TODO: Look into what changes/shapes waveforms Triangle is useful for frequency multiplication

Slew Effect

Trigger Extractor

DC-Offset Remover

TODO: See whether this is useful, what an implementation would be, whether just a cap in series inbetween the in- and output would suffice so it'd be useful

Portamento Adder

Simple Passives:




Signal Selector

Signal Switcher

Signal Copier

Suite of Connections

Visualizing / Analyzing Gear


Buy Chinese oscilloscope kit on aliexpress, make new front panel Maybe change firmware? Sell as kit? Could maybe be used as tuner, with changed firmware



Level Translators

  • What CV/sound levels will I even use?

Input Controllers


  • polyphonic
  • speed/force-sensitive
  • gate output
  • digital scanning

Ribbon Controller

  • pressure-sensitive
  • gate output
  • polyphonic????
  • also known as:
    • linear controller
    • stringer



Early Experimental Instruments

  • trautonium
  • hellertion
  • crea-tone
  • oscillion
  • emiriton

Drumset-like thing

MIDI-CV Converter

CV-MIDI Converter

Ring Modulator

  • No clue what this is, apparently useful for synthesis

Complete Synth Voices

YM3812 (OPL2 aka "SoundBlaster")

  • YM2413: same thing, but you can only configure settings for all voices at once
  • Use a kit? (20 dollars + shipping costs) #### YM262 (OPL3)
  • Lunetta


  • CD40106
  • CD4093 #### Counters #### Sequencers
  • 4017 (baby8)
  • dual 4017, with 16 steps
  • frequency divider with a mux #### Stepped Envelope Generators

Slew Limiter

  • synthcrap's design ### Function generator
  • synthcrap's design ### Gate to Trigger ### Logic Modules
  • Quad AND
  • Quad OR
  • Quad NOT
  • Quad XOR


  • sliderpots
  • exponential pots
  • other jacks
  • switched jacks
  • rotary switches
  • YM3812
  • YM2413
  • YMF262


  • Electronic Music Circuits, chapter on filters
  • Analog days, page 149 ext, 132 int

  • Wireless World, the circuits by Tim Orr