[sdiy] asm2 vco problems

[Ian Fritz]

At 09:14 AM 11/7/2008, Dan Snazelle wrote:


>anyone around here built the asm2? having some real trouble with the vco 
>(vco 1)
>
>the schematics are here:
>
>http://www.elby-designs.com/asm-2/vco/vco-asm2-about.htm
>
>
>getting voltage on all the rails.
>
>oddly the outputs (square wave specifically) keeps putting out  a 
>voltage...around 4 volts

This looks like a very common problem people have with modifications to 
Terry's design.  The reset pulse is probably not long enough to discharge 
the integrator cap. The solution, if this is the problem, is to increase 
C111 a bit to make the reset time longer.  Try 27p or 33p.

In his original article Terry wrote "do not change anything".  There was a 
reason for that.  :-)

   Ian