Hey all -
I am an engineering student taking an Analog to Digital class and decided to build a very, very simple analog synthesizer as my final project.
I have 4 months to build this thing - my goal is to produce a true analog sound, amplify it with an Op Amp, and use high resolution potentiometers to play with sound. Ideally - I would like this synth to be a 5 key keyboard that uses something like Cherry MX swtiches.
Once that is accomplished - I plan to use clocking signals combined with a series of AND gates and memory to achieve some level of basic Digital Signal Processing downstream. Haven’t really figured this out - but I have a bright team member spearheading this part.
My question to this community is: how can I create a true analog sound using simple components (oscillator, resistors, and potentiometers)? Stating with a single note, how could that be done? A function generator? Then, how can I play two notes at once?
I have the ability to create decent quality PCBs once I have the modules down. Thanks for any help you can provide!
Look at some of these:
Selected synth related LMNC projects
The “Simplest Oscillator” is interesting but I wouldn’t try to make it the basis of a synth. For one thing it’s simple in that it has very few parts, but it can be tricky to get it working. For another thing its range is limited and it’s hard to make it work reliably to play different notes.
The “Simple 1V/oct oscillator” uses an AS3340 chip which might or might not suit you, it’s pretty much the core of a voltage controlled oscillator in a single chip and maybe you want to use something less “prepackaged”. But if not it’s a good way to go.
You might not need a voltage controlled oscillator, maybe a simpler oscillator would work for what you want, in which case there are other designs out there that are pretty simple (but more usable than the “Simplest”).
To play two notes at once you pretty much need two oscillators.
AS AnalougOutput sasy the AS3340 is the simple way to go, but I doubt that would get you any marks in your course, unless you use it as a base for something far more complex like a poly synth. there shoul be hundreds of designs out there for more basic oscilators , I built a function generator for my final school electronics project back in 1992 primarily using a 555 and 741’s
You can build an oscillator out of transistors. You can build one out of op amps. You can build one out of CMOS devices. You can built one out of a VCO chip.
There are all kinds of levels of abstraction and only you know what level is suitable for your project. Once you’ve decided that, there are lots of possibilities at each level, but until then it’s hard to know what to suggest.
Excellent information here - I appreciate the resources @analogoutput! This is going to be really helpful.
Its really cool connecting the dots here - @twinturbo we built a small function generator last semester using Multisim - really cool to see it working. I see now that Oscillators is are the integral part of a function generator.
Based on some of the videos - the sequence of what I want to do is as follows:
square + triangle + sin oscilator —> filter that “clips” resonance (single high resolution potentiometer perhaps) —> amplitude distortion —> another oscilator → voltage controlled amplifier
Considering that I have to achieve some level of DSP - would I be able to play multiple notes by utilizing digital components? How about combining notes?