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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
PWM on the CGS VCO
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numbernone



Joined: Aug 16, 2006
Posts: 477
Location: new york city

PostPosted: Tue Jan 26, 2010 9:44 am    Post subject: PWM on the CGS VCO Reply with quote  Mark this post and the followings unread

Going to begin wiring my first CGS VCO tonight (with some trepidation, as this module seems to mess lots of folks up!), and am wondering about the PWM.

The schem shows a pretty open ended input at PWM. Would it be correct at this input to add:

A. 100k pot connected at CW and CCW to +/-15v for inital PW
B. Input jack attenuated by a grounded 100k pot
C. Should these be summed thru common value resistors like 100k?

I built the boards and drilled a panel over a year ago that I am now revisiting and have forgotten what I already figured out.

Thanks, next I will be asking how to bring all the waveform levels to useful values!
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stewpye



Joined: Apr 30, 2009
Posts: 49
Location: Brisbane, Australia

PostPosted: Fri Jan 29, 2010 1:39 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi,

I haven't built the CGS48 VCO yet (have a few PCB's here), but looking at the schematic I think you'd really have to add a summing circuit to have an iniital PWM control and external PWM input otherwise you'd get interaction between them - even with series resistors.

If you look at the ASM1 schematic you'll see how they've done it.

Cheers,
Stew.
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andrewF



Joined: Dec 29, 2006
Posts: 1174
Location: australia
Audio files: 4

PostPosted: Fri Jan 29, 2010 4:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

have a look at this thread
Zthee's method is best.
Very Happy
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