Sunday, July 30, 2017


A Possible display option... Nice and crisp but still not too sure about the update rate...

Sunday, July 23, 2017

Votrax Oscillator

One of the things that I have been looking at to extend the Galon Oscillator suite is a simulation of the 80's voice synthesizer, the Votrax SC-01A. A chap called Olivier Galibert has been busy un-potting one and reverse engineering the design in conjunction with the patent information. It has been made part of the MAME game engine from where I have taken a snapshot to further tweek into Galon land...
This is the generated transistor logic map from the die image. The most important aspect of this is the ROM table values which weren't in the patent... The code for MAME, which is on GitHub, is a very interesting read. I plan to implement it using some of the MI code such as the noise generator and filters... anyway a work in progress...

Wednesday, July 12, 2017

Still here...

There has been activity just not very well documented... A STM32 version of GALON is being tested but the inter-wiring is messy... I am now looking at a scaled up version that is Euro and going a bit crazy with performance. I am looking at a more robust rotary pot as well which should help some of the mechanical issues... Here is a bit of a 3D view:

Friday, June 3, 2016

Display #4 Dotz

Well got the 4th display up and running. Now wishing that I hadn't decided to use an AVR Tiny as it has a very limited ability to address large const arrays... I ended up getting the Ruby script to generate a huge nested case statement instead... messy... should have gone for one of these instead as they are available in the same SOIC 14 package and I think they are cheaper!

 The display does look quite attractive though!

Waiting on the digital rotary pot to arrive. Of course the AVR Tiny I2C code is also different from the other 3 as well... Oh well... Only found one mistake in the PCB this time and I can fix that in the code this time.

Tuesday, May 31, 2016


Have been going through the various voices and trying to understand how they all work and have been scratching my head and doing some reverse engineering of the mathematics. This is the filter out of TOY* that is from the coefficients back through MATLab.

Sunday, May 29, 2016

Stellaris Galon

Dragged an old friend out of the junk pile and press ganged it into Galon operation. I will put a 2 x 8 0.1" connector in the corner and try the UI as well. It will never really be a easy DIY build as any PCB will have to have the 0.5mm pitch processor... It is available in 64pins so not too many connections to get right and  maybe I will do the whole analog front end in surface mount as well...

Saturday, May 28, 2016

Rise of the Dotz...

Well the Dotz Display PCB's were back in no time at all! So quick they have beaten the parts by about a week! Oh well...

I also decided to pension off the old DIY Braids that was a bit of hacky mess of Nucleo board and this rats nest of wires. It never really worked very well and was particularly noisy... Still it got me on this adventure.

Thursday, May 26, 2016

Folding the Wave

Slowly cranking through the remaining Oscillators that I hadn't got going before. I am now into the Analog Oscillators as appose to the Digital Oscillators.  These are used to make more traditional Modular VCO sounds. I am always amazed that when I think "Oh I can add..." to the oscillator I find that Oliver has already got it in there! This is a case to point, I was thinking lets make a wavefolder like the Buchula 259 as a voice... While rummaging through the Folded Sinewave Oscillator FOLD I find that it is already here! The wavefolding transfer function that Oliver uses is a clever mixture of a modulated sinewave draped over a arctan transfer to achieve:

Which bears a close resemblance to:

From Jürgen Haible's Wavefolder A, described here. Jürgen typically went on to make Wavefolder B which is a fairly insane beast!