Friday, March 12, 2010


wow, its been a long time since i have posted anything here. i have mostly just been doing custom projects and odd jobs for people for the last couple of months. nothing worth posting. actually, now that i think about it i probably should have... oh well. this most recent project is definitely worth blogging about. this piece was a commission for a loyal enthusiast and valued customer of mine. i cant remember what the original criteria for the synth was exactly. im not even sure if i came close but hey, this is a sweet synth.
the synth is based around a very generic toy organ chip. i used the same chip in my "rainbow synth". the main voice is sent to an envelope follower for the attack release generator and also to a frequency divider where it is divided 8 times. each octave has a volume control on one of two axis of a joystick. the 8 octaves are then mixed back into the filter. the filter can also be modulated by one or two LFO's: LFO1, or LFO2 gated by LFO1. changing the GATE TIME pot on the AR generator will alter the AR generators response to the LFO as well, giving it even more diverse trigger sequences. the two LFO's also trigger the 8 step sequencer. you can choose LFO1 or LFO2 gated by LFO1. there is also a switch to allow the sequencer to be triggered by the main VCO just after the frequency divider. this makes for some INSANE timbres. this particular toy organ chip has got a few irritating setbacks. for one, in order to get 8 good sounding octaves from the divider, the chip has to be clocked pretty high, which is good because the action was pretty slow, but there was this sleep timer that went off literally 1 second after hitting a note. i built a simple lfo and sent it off to some redundant IO. it did the trick. another problem was the key hold. every keyboard with a sequencer should have a key hold switch to hold down the last key you pressed. usually you can just wire a switch to an unused key and it will switch to whatever key you press last. not this one though. it holds one key and one key only. i used a 12pos rotary switch for the key hold on this one. 9 of the 12 positions are connected to f#,g,g#,a,a#,b,c,c#,d. they can also be switched to a,a#,b,c,c#,d,d#,e,f of one octave lower. all issues fixed, this is sweet sounding little synth, especially with the added echo circuit. i had a few pt2399s laying around so i figured id throw one in. it is pretty excellent. i think i'll put a pt2399 in all of my projects from now on.
so from left to right the functions include; SEQUENCER switch with led indicator OFF>LFO1>LFO2viaLFO1, 8 step sequencer pots, VCF switch with led envelope indicator ECF>LFO1>LFO2viaLFO1, LFO1&2 pots, AR gate time pot, attack pot, EG depth pot, release pot, resonance pot, cutoff pot, power switch OFF>ON>ON/KEY HOLD OCT^, master volume, pitch bend, key press indicator led, main VCO trigger sequencer ON>OFF, echo feedback pot, echo rate pot, 4 joysticks for 8 sub octaves, rotary KEYHOLD switch, and finally a 1/4" line out.
this keyboard was all fitted into a travel size backgammon case that i found at goodwill. its actually pretty decent quality pleather. the panel was BOUGHT... yeah, first time ive ever had a piece of plastic cut to order. it was actually pretty easy. in fact it was a hell of a lot easier than cutting it by hand. only problem is it cost $50. ouch...
uuuhhh. ok, i feel like ive been typing forever even though ive only got like two paragraphs. forgive my A.D.D but its beer time. here are the pics and video. please comment.



  1. Your posts are a wonderful mix of inspiration and frustration.. As always, brilliant and beautiful work on every level..

  2. This synth is beautiful and very creative! If you could help I would really appreciate any pointers at getting started with vco's etc.. and adding my own circuits to toys. Your blog opened up so much inspiration.. unfortunately much of it is over my head. I have bent many things and I definitely love the hobby and am devoted (:
    sorry for the long comment, maybe just shoot me an e-mail if you aren't too busy?

  3. Hey man i love your stuff. you are a artist! i have a band im putting together and we have some stuff we want your touch on them. send me a email so we can talk business.

  4. I noticed that this particular synth has batteries... do you ever use wall warts with your projects?

    I wanted to know because I want to hook some of my projects to wall warts and I am afraid to fry em.

    Any pointers???

    You rock!!!

  5. you can always add an AC adapter to anything that takes batteries. you just have to make sure the voltage and the polarity are the same. i dont like using AC adapters because they usually overheat and fail or put out too high or too low of voltages. they can also cause a lot of buzzing if the mA's are too low. i would stay above 900. an assortment of decoupling capacitors in the circuit will help too. when i use AC adapters, i usually use voltage regulators in the circuitry. this usually helps to keep the voltage consistent. it is possibly to fry sensitive chips with ac adapters. make sure it's connected properly and get to know the ciruit before poking around on it. hope this helps.

  6. i want to get such a nice synth and live in germany, is there a possibility?

  7. This is awesome! Came here from your youtube channel. Any way this thing could be made again? I'm drooling!