yeah, i've been dreaming of this for about the past year...now i am going to DO this! i have placed orders with jameco, bg micro and effects connection (they have 3pdt "mxr" style switches for $3 each! best price i've seen!).
i am going to start with the VCO and the keyboard. i will be using reed switchable keys i harvested from a lowery organ. so, they keys shall have a nice weight to them. the voltage controlled oscillator will be 555 based. a part of me would like to run a parallell circuit with trimmers from the pitch point of the circuit to the keys, to keep that mono-synth vibe. but, as i have been told multiple times, it would probably not stay in tune. so, i will be using a 74c922 key scanning chip. i do not know, but i have a feeling it will not be mono...sigh. input?
once i get the keyboard going (the case will be built, etc by now), i will start experimenting with the filter and lfo! i will prolly build different versions of filters, but my first lowpass will be based on a butterworth lowpass in an IC! i didn't know there was a chip for this! wow! it sould be easier, i would assume.
there will be an LFO to add modulation to the pitch of the VCO and the cutoff of the VCF. i'll use a patch cable and jacks to connect to the cutoff and the pitch.
also, a point to ponder (as well as a decision which should already be made!) is, how many keys should this have? the keysets have 3 octaves, but i would like to just do one octave, c to c. in order to do this, i'd have to actually CUT the circuit board which the diodes and reed switches are connected to. hack saw?
i will be doing bass pedals as well.
anyhow, your input please.
Please provide build photos!!!!!! I've actually been planning something very similar for the past few weeks. Let's trade info :)
Could go for dedicated knobs for the LFO->Pitch and LFO->Cutoff, might be cleaner than just having the three patch points. That is, unless you plan to gradually expand it into a more modular system, but as you said you're buillding it into a case as well it sounds like a self-contained thing.
Also, I'd go for at least 2 octaves if you can, would be a bit more playable.
Should be a cool project though!
good advice on the dedicated lfo pots. the monotron layout is a switch between the pitch and cutoff. this seems more versitile! i feel like if i had the cable/patch system, i could get more experimental as i add other filters, ring modulator, etc.
i may just do 3 octaves, since the keyboards coming out of the organ are already set up that way. but this is more for plays simple melodies, leadsynth sounds and making noise! i also like the idea of it being more compact. i want it to be a monosynth, as they have more character as a lead synth, and sound a bit more vintage, in my opinion. can this be done with this keyscan chip?!! can i just skip connecting from key to key in series, and just run parallel to the chip?
i'll take lots o'photos and maybe some video! i am going to be totally learning this stuff as i go, so i may not be the one to follow! i need to follow you! lol
Sorry to bring this one back form the dead, but I built this thing a couple weeks back and thought it would be a nice addition to this thread.
Select-O-Rama (http://www.youtube.com/watch?v=Hx62HeB-xvw#ws)