[sdiy] best soundign vco design?

[James Patchell]

While it has been pointed out that if you jump through enough hoops, it is 
possible to make a half way decent VCO out of the 8038, I would say don't 
bother.  By the time you add all of the stuff you need to actually make it 
work, you are better off having just started with a well behaved oscillator 
like the Terry Michaels (ASM-1) type oscillator, or, if you are a fan of 
triangle oscillators, an OTA based one ....  by the way, you don't need to 
use an LM13600/700, CA3080, or the like...I use a pair of matched PNP and a 
pair of matched NPN transistors to make an OTA cell and it works quite 
well....although, I use the THAT140 for the matched transistors.  There are 
schematics somewhere on my website...


At 11:18 PM 6/11/2004 -0400, Roy J. Tellason wrote:
>On Friday 11 June 2004 11:02 pm, Mark Romberg wrote:
>
> > what about the nat semi ICL 3038?
>
>I didn't know they made that part...
>
> > it outputs square, sine and tri simultaneously and isnt quite as hard to
> > find as the 13600/13700. there's a decent looking schem for a VCO in the
> > application notes that you can get from NS.
>
>Got a link to that app note?  I got one of these parts at Radio Shack some
>time back and built a crude function generator around it,  but never thought
>about using it in a VCO.

         -Jim
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