555 Additive Synthesis

Thread Starter

Vincent Lembke

Joined Sep 1, 2019
1
Greetings fellows!!

It has been a long dream of mine to build my own analog synthetizer, and now that i have got the time, i want to finally make one!
I am thinking about building a fairly simple one, with two or three oscillators, High and Lowpass filters and a basic envelope generator.
I came across a circuit based on the 555 timer IC to build a toy organ. I would like to build it and have this as my wave generator.
I fairly know how to generate the diferent wave types, i.e., Square or Sine. But i would like to combine two or three of these waves together to a single wave that goes through the different organ keys and posterior FX.

Can i build two separate 555 circuits and somehow add the waves generated?

Somehow i can´t find any Info anywhere on this topic...

Thanks a lot! maxresdefault.jpg
 

ScottWang

Joined Aug 23, 2012
6,963
An output pin of 555 connected to another 555 of its control pin (pin 5), it can be as a wave modulation.

A square wave through a LC circuit then it could output a sine wave.
 

Alec_t

Joined Sep 17, 2013
11,755
Welcome to AAC!
But i would like to combine two or three of these waves together to a single wave
It depends what effect you want, but for a pleasant result methinks the waves would need to be harmonically related. Drift of the tone-generators' frequencies would affect that relationship. Keeping 555-based analogue tone-generators in lock-step would not be straightforward.
 

danadak

Joined Mar 10, 2018
4,057
An alternative is to use DDS generators that have precise divisor
values that can be run off a crystal.

Do you have any processor experience ?



Regards, Dana.
 

AnalogKid

Joined Aug 1, 2013
8,706
Somehow i can´t find any Info anywhere on this topic...
A 555 can drive a small speaker directly, but that is not what you are doing. Consider the 555 output as just another audio signal source. Search for 'summing amplifier schematic', audio summing circuit, etc. to get lots schematics. You will see that most of them are based on the same basic principle.

For your 555 circuit, is it important to have an adjustable duty cycle, or do you want an symmetrical (50/50) squarewave at all frequencies?

ak
 
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