sábado, 24 de septiembre de 9707

Home made analog syntheziser

I began this project when I was in High School, near 1992. I had skills in electronics, computer programming and music, and I liked the idea of build an analog synth.

In that pre-Internet era, at least in Argentina, I had to design everything by my self, of course, in a prove and error way.

The first design was the VCO. There were many versions. At first I build a V/Hz oscillator (or almost that), and then a hi-freq VCO that clocked a counter that produce many simple wave shapes via a R2R network (A kind of sampling). Those designs didn’t like me at all, and had many problems.

Then I build a "discrete computer" with many 74HT series IC's to scan a keyboard and produce a Hi-note priority VC and GATE signals. This circuit, with little mods, is now working in the synth. Of course, a microcontroller can do that in a simple way, but I knew them many years later.

In the middle of the 90's I had access to the Internet and could learn how to design a 1V/Oct VCO and a Moog type VCF.

In 2000, I had many designs and circuits tested, so I decided to put them in a cabinet. I bough a not-working Casiotone in a music store and build a wood cabinet. I put everything inside and hardwired each PCB. I design the front panel too, using MS PowerPoint.

The years till now I introduced many improvements, like a more stable VCOs and a Microcontrolled MIDI Interface, that also replace some instable analog circuits, like Transpose and 0800 DAC´s that has a poor performance cause its relative hi error tolerance.

I can say the project is ended, but there are many things I'd like to improve in a future, such as LFOs and Envelope Generator. I suppose I'll do it sometime.


3 x Analog VCO:
Sawtooth, Pulse w/modulation, triangle
2 modulation channels for each one
Individual transpose: +/- 2 octaves and free
Hard Sync
1 x White Noise Generator
1 x External imput

1 x VCF (4 pole Lo Pass): Moog clone filter w/ 2 modulation channels, and resonance, cut off and envelope amount controls.
(The mixer overdrive the filter producing a very nice overdrive effect, similar to valvulated amplifiers)

1 x VCA w/ 2 modulation channels,

2 x LFOs

2 x ADSR envelope generators

MIDI IN: Note, Pitch bend, Cut Off and Modulation controlled vía midi messages.

Other projets:

These are other synth projects:

-Analog Guitar Synthesizer: it's a simple overdrive-distortion effect box. I put many type of diodes to get different clipping configurations. It has also a tone control and a hi-pass filter in the input.

-Analog electronic drums machine. I had the schematics but only build some parts. I don't thing that I'll finish this project.

-Polyphonic synth: I'm in the beginning of this project. I just design de DCO's (a super stable analog VCO, hard synced with a microcontrolled pulse) and a VC Wave shaper. I'd like to build a polyphonic synth with 100% analog audio signals voltage controlled by a 16-bit microcontroller to get pitch stability, complex patches and modulation capabilities (LFOs, Envelope Generators, Modulators, etc are generated in the microcontroller so there are infinite possibilities of modulate a real analog sound). Now is only a project and I have some schematics but I’m not intended to build it in a near time.

2 comentarios:

vinnui dijo...

Excellent work, keep posting!

Jaide Zone dijo...

I would love to see your tips on building a 1v/Oct VCO. I have failed this many times. I would love to try to build your VCO