Cgs synth

ok, so on the schematics the biasing resistors are the 240k to -, and
the 330k between pins one and two of the 072. Elby instructions say
to replace those w/ 270 and 560.
I replaced the 240 w/ the 270 and the 330 w/ the 560. This is when I
had the clipping problem.

I decided maybe its time to read the ASM-1 instructions, so I did, and
it talks about having a 560k resistor to the - supply. SO, ive gone
back and replaced the 240 w/ the 560, and the 330 w/ the 270.
Everything looks good this way on my scope, but the output is higher.

But, now the square output seems to be really high (almost all over
0v) and the PWM control doesn't work the same way.. it would sweep
from all off to all on. Now it sweeps from 50% to all on (100% duty
cycle).

Is this correct? the resistor changes are backwards from what I
thought I was supposed to do. Im going to leave it like this for now,
but please tell me if it is wrong.

Scott

Hi Scott,

You have those 2 resistors back to front. The 330K should have been replaced with the 270K (although 200K might actually be better) and the 240K should be replaced with the 560K.

If you look at the ASM2-VCO you can see what I mean. Note that I have a 200K resistor in place of the 330K and have a trimpot and resistor for the 560K (which is now nominally 440K)!!!!!

I will update my notes to make this more clearer

Best Regards

(Mr) Laurie Biddulph
Mobile: 0404 846 943

Elby Designs
ABN: 70 022 727 605
http://www.elby-designs.com

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