WGTP Sonic Assaults CMOS DS1 plus mods

[anders]

I did ROG 22/7 the other day and I instantly fell in love with it! Then I did Way Huge Red Llama and man, what a great overdrive.

So I decided to scan the net on CMOS based distortions and overdrives and stumbled on this.
CMOS DS1 Schematic

Drew a layout and built it and it sounded decent, pretty true to the original which meant I had to modify it.
Changed input and bypass caps to larger values found in the old MIJ version and swapped the silicon diodes for orange LED's. Now it's a loud and and quite evil fuzz perfect for down tuned heavy stoner rock.

Vero with stock values.


Vero with mods.


Both are verified, now I just have to add a gain control...

[Sphere80]

Thanks for doing this!.  Really, sounds close to the ds-1? interesting.  I like the ds-1 and have been  interested in csmos designs.  Any clips?  Thinking ahead, how would one squeeze out more distortion? I'm sure it's plenty heavy already.

[anders]

Well, not really THAT close, smoother and a bit fuzzier I would say. Still it sounds quite good.
I don't really know much about CMOS circuits but for more gain you could probably replace the 470k resistor with a higher value? Red Llama has a 1M pot in this spot. It's also worth decrease the 4,7k resistor that goes to the 470nF cap. Subbing the silicon diodes for LED's really make it more aggressive and heavier.

[Frank_NH]

Interesting design!  Another thing you may want to play with in this circuit is the supply voltage to the CD4049UBE.  Generally, they like it around 5 - 6V, so instead of the the 10 ohm resistor in series (first layout) with the 9V input power, I would try 220 or 330 ohms (which you have in the second).   The Red Llama uses 1K!.