I’ve been using and enjoying modular synthesizers to and from since many many years, from a fully DIY modular (seen at the back) to a modern Eurorack system where some modules are my own design, some are DIY kits, and some factory built modules.


My own design. One module, three functions.

The LFO is a typical standard LFO with saw-tri-ramp shape, as well as a pulse/square output.

The slew limiter and envelope generator allows linear or typical RC-curve.

The envelope generator has two attack modes: Gated, where the attack phase is cancelled if gate goes low, and Triggered, where attack phase always finishes until it reaches the target peak voltage. The sustain knob controls the S level. At 0% it gives an AD envelope, at 100% an ASR. The shape knob controls the balance between A and D/R. So D and R has the same time, just like on the minimoog. In Triggered attack mode, the attack phase always finishes even if the trigger/gate is shorter, this makes it possible to use as a clock divider or “subharmonic generator”.

So the shape knob affects the waveform shape for all three functions. Same with the rate knob and range switch. The lin/log switch affects both the slew limiter and envelope generator. (it needs to be in LIN position for the LFO).

The RISE/FALL outputs put out a high gate when the output is rising or falling, and works for all three functions.

It’s 8 HP, and about 38mm deep with power cable inserted. Power consumption is about -18mA / +20mA.

Build your own

Contact me if you’re interested in buying a PCB/panel set.

BOM is available here: LFOSLEW_BOM_1.1.pdf


My first (but hopefully not the last) collaboration with RYO, 2xVCX eurorack module!

It’s a dual four-quadrant multiplier / VCA / crossfader.

See schematics here (PDF).

12U x 126HP foldable case

This is a foldable eurorack studio case. I designed the model in SketchUp and had a friend cut the material with his CNC machine. He also mounted the pieces together. It features 2 x Doepfer PSU3 power supplies. Here’s the plans (PDF).

Old stuff

The stuff below is mostly here for historic reasons…


My homegrown analogue modular synthesizer.

Madmouse 1

A madmouse kit modified to semi-modular. This was a simple little synthesizer-kit that I built and modified from prepatched to a semimodular synthesizer.


Portable semi-modular synthesizer. This was a simple little synthesizer kit (madmouse) that I built and modified from prepatched to a semimodular portable synthesizer, housed in an aluminium case.

Kymatica SDS-800

Modified Simmons SDS-800. Work in progress.. The sds-800 is a drumsynthesizer with four voices (bassdrum, snare, tom1, tom2). Each voice is based on a CEM3394 chip, which is a whole little analogue synthesizer in one chip. Each CEM3394 contains:

But in the original sds-800, most of those features was left disabled and unused.


Noise-machine I built for my friend Daniel Karlsson on his birthday. The Trashofonium is a modified EQ with internal electric feedback, it also has sockets for connecting external gear into the feedback loop


A cracklebox-like noise machine built of a radio. A small battery-driven AM radio can be a very interresting musical instrument after some circuit-bending… Simply find the best nodes on the circuit board and solder wires out to some touchpads made of screws fastened through a wooden plate.


An USB control interface. This is a controller with 6 analog and 10 digital inputs, with an USB connection for controlling custom software on the computer. The analog inputs are 10 bit resolution, and connected to 4 knobs and 1 joystick. 8 of the digital inputs are connected to toggle switches, and the remaining 2 to push buttons. The serial protocol used resembles MIDI but is faster and higher resolution, 10 bits instead of 8. It’s based on the Arduino microcontroller board with an AVR atmega168 processor. No batteries needed, it powers on USB.


A 12-stringed instrument built from old guitar-parts.


Manual gate with individual levels for on/off state.


A small and simple noise generator.


The brother of Trashofonium, featuring feedback and momentary push buttons to cut specific frequency bands. Built for Martin Öhman in The Moth.


State Variable VCF

Based on CA3080. I never got the resonance to work as I want it. kymatron-vcf1.pdf

Dual State Variable VCF

Based on SSM2164. Works much better than the CA3080 SVF! kymatron-vcf2.pdf

Dual State Variable VCF and 1v/oct quadrature vco

Based on SSM2164. An enhancement of the filter above. This one features stable selfoscillating and 1v/oct cv-inputs. It doesn’t go very high in frequency when oscillating, but is a very useful module anyhow… kymatron-svf-vco.pdf

Bipolar mixer V2

A very handy thing, each input has a scaleknob with “-/0/+” so it’s easy to invert the signals. Each mixersections output is normalized to the next section, so that the sections link together to form as many mixers with as many inputs as you need… One channel on each section is normalized to a fixed voltage, so it can be used to add an offset voltage.

Quad fourquadrant multiplier

Built around MLT04 multiplier IC. This module may function as ringmodulators, VCA’s, VC-crossfader, VC-panner, frequencydoubler (with sine input) multiplier.pdf

Voltage controlled switch

Built around MAX4533 electronic switch IC vc-switch.pdf


Built around MAX4533 electronic switch IC. Very bad drooprate, maybe some better opamp-buffer and/or capacitor should do it… 4533-SH.pdf

Percussion Envelope

NOT TESTED. The idea is to have two alternative decay-times to choose between with logic input. perc-env.pdf

Computer Interface

This interface connects to the centronics parallel port and outputs 8 channel gate and 4 channel 1v/oct CV with 12 bit resolution. Based on MAX536 Quad ADC and 74LS244 Octal Buffer. I’ve redesigned this to use an Arduino over USB port instead, since todays computers does not have parallel ports.. pc_interface.pdf

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