Wednesday, 23 May 2018

It's 555 .... resonator (Eurorack version)

This is a set of five 555 based one shot circuits.
Each has CV and pot controlled pulse width and the pulse for each can be set to be negative going or positive at any desired amplitude. The circuit is supposed to be driven by a signal from a VCO, but noise or chaos sorces are fun too. It creates five pulses that can be individually manipulated to create a complex and harmonically rich waveform. A slower clock signal will give clicks and glitches (so, a voltage controlled glitch module).
As the pulse widths can be individually controlled (or controlled en masse by “CV all”), this waveform can be continually morphed to get new sounds. When the 5 pulses are quite thin the effect is that of a resonator. The controls allow a wide pulse width, so fatter, thicker sounds can also be created.
Panel = USD24
assembled = USD230 

Tuesday, 22 May 2018

Kareishuu VCO

PCB set = USD23
10HP Panel = USD22
assembled  = USD210

This VCO was mainly designed as an upgrade for the dual OTA VCO. It is a traditional triangle core VCO with a built in VCA for the FM control section. The design draws on sections of the Electronotes EN1, EN2 and EN3 VCOs along with some NLC injected in there for good measure.
It has much better tracking, a sine output and attenuators for all inputs. The self modulation control via the FM VCA enables voltage controlled waveshaping, the sine and tri waves can morph between their original shape to a pulse.

The pot spacing is quite tight, so I suggest using T18 knurled shaft pots along with the micro knobs. Other than the 1k tempco, no rare parts and a fairly easy build.

Friday, 27 April 2018


Panel = USD20
Assembled = USD160

Not trying to get all MI-y with the name, it comes from the children's game also known as Red Light Green Light.

This is a 1 to 8 multiplexor....or multiplexer if you prefer....with a thru and hold circuit attached to each output. the active output is chosen by whichever combination of the x00, 0x0 & 00x inputs is high. You can put any signal into these, crossing 1V will send it high. In the demo video, I used the /2, /4 & /8 outputs from a Divide & Conquer which gives it a regular 1-8 count. Using any old signals will give a more random effect but patterns will still emerge.
IN is the signal getting processed.
This module can be used to process CV and/or audio signals.

Build guide and panel template on the NLC wiki

The 1st part of a video shows a sine wave being re-constructed when the 4 outputs are aligned on the 'scope.

Tuesday, 10 April 2018

Ian Fritz's Hypster

Ian Fritz designed an awesome hyperchaos circuit and gave me the go ahead to let it loose on Eurorack.
You can read the discussion on this design on the muffwiggler thread
This is Ian's introduction in his article on the circuit: The Hypster is an electronic fourth-order hyperchaos generator for use in modular electronic music systems.
Hyperchaos is chaos on steroids, with the mathematical divergences being generated in more that the usual single dimension. The module is a unique, original design featuring voltage control of the main system parameters.
In synthesizer applications this module can produce signal waveforms varying from simply periodic to complicated multiperiodic to extremely dense and complex, both in the low frequency control range as well as up into audio frequencies. With an eight-signal output it can simultaneously control a large number of synthesizer parameters or generate multiple audio waveforms for individual processing.
The circuit is built around four voltage-controlled integrators connected in a ring, similar to the configuration of an oscillating ladder filter. But that is where the similarity ends. Each integrator includes damping, making the system more like the 6/8 phase oscillator described on my website. Most importantly, special circuit elements between the four integrators provide the nonlinearities required to produce chaotic oscillations. The gain and resonance of one of the stages may be varied. Varying these parameters produces a wide range of periodic and chaotic signals. These
parameters, along with the overall oscillation rate are under voltage control. 

It is very wide ranging, from approx 3kHz down to 5 minute orbits, capable of a huge variety of patterns and is particularly partial to being controlled by various CV signals.

PCB set = USD26
White Panel = USD24
Black Panel = USD25
assembled = USD250

Sunday, 8 April 2018

Let's Splosh!

This is 8 different rectifiers processing 4 input signals. It is happy to work with audio or CV or both at the same time. It has 16 outputs that will deliver 16 different signals made up of components of the 4 incoming signals. To put it simply, it makes a gloopy mess of the incoming signals and smears it all over your patch. If this module name and the food names make no sense look up some sploshing videos on youtube. That is pretty much what this module will do to your CV and audio signals with corresponding amounts of pleasure for the receiver.

panel = USD24
assembled = USD180

Build guide is HERE

Friday, 23 February 2018


PCB set - USD23
Panel - USD20
assembled - USD200

This uses the core circuit of the Korg 3100 Resonator, with component choices for the filter sections as per the mods introduced by RJB in his blog back in 2005.
The main difference of this version is that it has 4 VC bandpass stages and a feedback control, the original has 3 stages and no feedback. The 4 VC bandpass stages can be controlled by a single CV on input 1 (with an attenuator) or individually with each of the 4 CV inputs.
The CV processing sub-circuits are greatly simplified from the original Korg version, simply using op amps to drive the vactrols.
The 2 inputs are summed together. Out 2 is an inverted version of Out 1.

Thursday, 15 February 2018