[sdiy] ASM-1 VCO

[Oren Leavitt]

Hello,

Are you saying that the pulse width sweeps over its entire 100% range within a small 15% range movement of the pulse width control?
Or is it just the difficulty of getting it on the 50% perfect square wave mark that's troubling you?
Would adding a separate comparator with a dedicated 50/50 square wave output help?

If it is over responsive, it could be that the signal going to the pulse comparator is very small.


Oren

-----Original Message-----
From: "Brett, Bill" <BJB at dolby.com>
Sent: Nov 17, 2003 2:14 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] ASM-1 VCO

Greetings,

I have built up several ASM-1 PCB's and the VCO pulse width modulation control does not work as I would like. A control signal from an LFO will sweep the PWM control until the square wave output goes to the power rails. There is only a narrow range in the middle of the control signal swing that results in a square wave output. I also used a 100k pot to set the PWM manually This control also has a very narrow range (about 15%) that results in a square wave output before the output goes to either of the power rails. 

Does anyone have advise about modify this part of the VCO so that either control does not shut down the square wave output. 

Thanks

-Bill

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