| GUITARI 2600 MONOSYNTH Monophonic Guitar Synthesizer Created Using CMOS Chips |
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In my crazy internet travels looking for circuit design information, one thing that everyone seemed to be getting into after awhile, has been monophonic guitar synthesizer pedals, which now, as of 2023, have been long since overcome by DSP modeling based polyphonic synth pedals. So why am I designing my own when I can go fork over $200 to BOSS and buy a Synth-9? Well, because I've put THAT much effort into this BEFORE the Synth-9 came out, and I will continue to design my own synths, because this one came with a bigger purpose.
My initial ideas for guitar synthesizers were taken from Parasit Studios 4046 based guitar synthesizer, a simple hex inverter, a CD4046 for sample/hold, and I believe a third chip for octave up. Anyway, this design was inspiring, so I tried it with the "Gain Boy" and failed because I just don't have the know-how....if only there was a simpler, more direct way. One thing I understood was Fuzzes are very gainy, and they generate a "Square Wave". Now, if I could just "naturally" turn a guitar sound into a straight up square wave stable enough to sound like a video game cartridge from 1977, and not a guitar, then we might be on to something.This is My Second Synth - Design Process My first synth was the "Gain Boy" which just sounded like a Nintendo Game Boy pretty much on ONE of it's channels, this thing could do a heck of a lot more. And it's kind of a combo of self-education put into action - basically, a very complex, monophonic, guitar synthesizer, that sounds like an Atari 2600 console (only one of it's sound channels). Where this whole mess got started was this video.....and the crazy ideas in my head resulting from it from now understanding (somewhat) how synthesizers AND darned well how Electric guitars work. The heart of the beast is the CD40106 CMOS Schmidt Trigger/Hex Inverter. I got the idea to use it from the video above. Basically, you create an oscillator using the Schmidt Trigger/Hex Inverters on the CD40106, of which there are SIX. Hmm...and how many strings do we have on a guitar - SIX - do you see where I"m going with this? Since voltage controls the oscillator.....what does a guitar produce? Voltage! And what do we do with that Voltage? Oscillate the Hex Inverters. What I figured out was 2 methods to do this - one is slam the first oscillator to death - hardcore - with a Op Amp of some kind, like an LM386, the other option was to slam the signal with an Op-Amp to put out enough voltage to drive all six oscillators - and use THAT for the chip's power source (CD40106). Kind of like what you do with the transistors in a fuzz pedal. |
