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A collection of my electronic projects over the years

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The Wonkinator -  CMOS 16 step sequencer with modded 808 Kick, Snare, Hi Hat and Open Hi Hat sounds. I built this after realising I don't have any analog drum sounds and needed something to go along side my SY-1 percussion and synths.

I was previously using the Octatrack for most of my drums but got annoyed at the fact there were no individual outputs for each of the tracks so it meant mixing/post production was a problem.

Features include -

- Individual 16 step sequencer for each drum module with step mutes,         adjustable velocity and step direction

- Adjustable clock divider for each module

- Adjustable step length from 5 - 16 steps

- Random Binary Noise Generator for random step select

- Burst Generator (Not completely working 100% yet!)

- Master clock with coarse and fine speed controls or can be clocked externally

- Individual clock inputs for each module

- Master step reset button and external reset

- Adjustable pulse width and delay for internal clock 

All drum modules can also be triggered externally bypassing the internal sequencer. 

You can get some strange rhythms with this module due to the fact that each drum can have individual variable step lengths while also playing different divisions of the clock.

Some very rough sketches and schematics of the circuitry I used. I should draw a detailed schematic at some point before I forget it all!

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Wonkinator Guts

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This is my main module that contains two CEM3340 VCO's, waveshaper, S&H and LFO, clock divider, variable state bank filter, four envelope generators and VCA's, Moog filter, two gated slews, CV inverter and four buffered outputs. This took me a very long time to complete as I was still learning a lot during the building process. Originally I made each module in separate wooden boxes which worked well at the time but wasn't very practical if I wanted to use them in a live setting. If I were to do this again I would probably not use 2mm thick steel faceplates as they were quite difficult to cut to shape and they also weigh a ton!

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The adjustable +/- power supply for my module. Before building this I was using cheap switchable power supplies to generate +/- power rails from AC wall adapters which worked fine to a certain point but I noticed they were susceptible to noise when more modules were added and more current was drawn. To combat this I decided to build my power supply from scratch using a toroidal transformer, adjustable LM317/377 voltage regulators and three 10,000uf filter capacitors for each rail. Still not a perfectly clean power supply but useable.

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A copy of the Pearl Syncussion Sy-1 from 1979. This is actually the Bergfotron clone that has a lot of updated functions that you can find here - http://www.bergfotron.synth.net/Percussion/super%20syncussion.html

I took this design and added some extra bits myself 

- a transistor switch resetting the LFO from the input gate signal

- a VCF cv input

- VCA cv input (this took me ages to figure out how to do it but I ended up using an LDR to control the PWM of a 555 timer which went to two separate NPN and PNP transistors that controlled another set of LDR's that connects to the + and - of the decay pot. This way the two latter LDR's flip flop between on and off controlling the resistance of the + and -. There's probably a far more efficient way of doing this but this method worked the best for me)

Syncussion SY-1 guts

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Dual 4017 based 10 step sequencer with separate gate and pitch outputs, CV slew and clock in/out. I designed this to be used with the SY-1 so I can use it as a standalone noise box! The internal clock is coming from a 40106 Schmitt-Trigger but can also be used with any external clock source. I've also utilised a secondary clock output from the 40106 that modulates the primary clock resulting in glitchy/wonky rhythms from the 4017 sequencer. The nine push switches on top also provided extra glitchyness to the pitch sequence by connecting more than one pin to the reset pin of the 4017

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The beginnings of an 808 drum module clone. I hope to build this into a standalone drum machine with each module having a dedicated 16 step sequencer. I'm going to look into using other logic chips to do the sequencing as I think the 4017 is somewhat limited.

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Books that I have found to be quite useful when I'm stuck and don't know what the hell I'm doing. I use the Art of Electronics book more of a reference as it's pretty dense reading! The Electronic Drum Cookbook by Thomas Henry is also really useful

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