Tuesday, 10 November 2015

CGS 58 Dual Utility LFO - build notes

I'm finally getting around to building one of Ken's modules.
It's his classic LFO (Cat Girl Synth 58).

First some unpopulated PCB pics.

 And the reverse side.

Headers first.

Resistors, diodes, caps, beads. There are no hard to find parts.
The circuit uses a Schmitt trigger  --> integrator  ----> comparator.
Check out Ken's schematic.
The 1st section, the  Schmitt trigger has a positive feedback applied to the non-inverting input.
In the  integrator , the feedback resistance is replaced with a capacitor and finally the comparator
kicks in  where we have no feedback loop. The comparator generates the square wave.

I've been getting a bit spoilt lately in building modules with surface mounted pots.
So decided to try adapting this.

You need to be careful with polarity of the LEDs too.

It seems to work well.
Now it's time to make the faceplate.

Some useful links:
1. Adding a range switch - Muffs 
2. Bridechamber
3. Adding CV control - electro-music
4.  Serge Audio & CV levels - muffs
5. Ken's own site - CGS
6. Video - youtube

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