Synthesizer projects


Neutron Shield Modulator: versatile arduino programmable synth modulator

The neutron Shield Modulator is an oversized  "shield" for arduino to interface with standard modular synthesizer voltages.

Youtube examples.
first test of prototype in synth.


Burst Generator:


1.0 prototype
The old and very complicated prototype:


2.0 Prototype boards
 the new version is a single board (instead of 5)which will be compatible with euro and MOTM/MU panels.
There are 8 LED potentiometers to control the parameters of the chosen program.
There are 4 switches to control program options
The only wiring will be to connect the input and output level and offset potentiometers, and the jacks
there is an 8 way selector switch to select which program you are using. the program number will be displayed by one of the LED pots lighting breifly when the switch is changed.

The new board will fit MOTM, EURO MU(dotcom) and FRAC panels.

with euro and frac, the jacks and analog controls would go to the side.

Much more low profile and also much easier to build. wiring has been reduced almost 10x

(note, the small board at the bottom, is just a "jack board" from something else, normally the jacks will be hard wired)

Front looks pretty much the same except the direct LEDs are added, and USB is no longer on this panel. a daughter panel with USB and MIDI could be created, or you can just run a USB cable out the back of your synth to plug in to a computer if you  wish to reprogram often.

(note only 3 direct LEDs on this version, I have managed to squeeze one more out of it)


2x CV 2x Gate/ trig

2x CV 2x Gate/ trig

controls, arduino program:
8 pots, 8 LEDs, 4 toggle switches

4 "direct" LEDs 2 are on arduino timer 2 pins 3 and 11 and can be PWM.

controls, analog
input level 1/2
input offset 1/2
output level 1/2
output offset 1/2

Voltage regulation for 5V digital electronics

+-15 or +-9v MOTM or EURO power.



In normal operation you would have 8 "subcodes" which you can select with the 8 way switch.

Depending on how the subcode is written the 8 potentiometers and 4 switches will alter how the subcode works.

for example the "dual ADSR" divides the unit in half, with the 4 pots on each side controlling the normal A, D, S and R amounts, with the 2 associated switches for each side selecting repeat mode on or off, and linear or "capacitor" type response. the 2 Gate/Trigger inputs trigger the respective envelopes, and the CV inputs modify the decay and release times.



Completed and planned Subcodes:

Dual ADSr with linear or capacitor response, gat>trig out.

Advanced ADSR with wobbulation on the attack decay

Rate + Level ADSR (like some old digital synths)

Dual LFO retriggerable LFOS with adjustable reset point. (CV frequency, input gate retriggers, square on gate outs)

Simple sequencer clock steps through pot levels with reset and reverse etc

voltage converter (scanner)

input monitor (check levels and triggers, digital pass through)

Chaos LFO multiple kinds of chaos (in this case one of the potentiometers selects the type of chaos like a swirch, the pot LEDs light for a short time to show which one is selected)

burst generator (output bursts of gates, (gates repeated on CV outs with varying levels, great for LPGs)

Subcodes gradually in progress:
( i am sure once some other owners who can code get hold of it they will come up with many more ideas)

simple "shift register" sequencer with voltage control of number, gate randomize etc

Hawkwind envelope/lfo (all set up to modulate a VCO or filter for those sweeps)

CV tools (panner cv outs etc)

dual CV gate stretcher

beat listener (tries to add extra gates in a musical way depending on input triggers or sounds)

envelope follower

midi controlled pitch reference



Tested Arduinos that work so far:



Uno 3.0

Freetronics "11"

Chinese duelminove clone.



Schematics PDFs  (work in progress)

Controls and digital circuitry

Analog I/O

Off board pot and jack wiring

power supply < not ready

2012 J.Matheson [DeFex,Neutron7]