Tom G's VCO-4d is working

[Andrew Schrock]

On Tue, 29 Jun 1999, Roy Tate wrote:
> I haven't heard anything either way from other builders, so I 
> thought I would chime in.  Tom G's VCO-4d worked fine for me.
> I went with the tempco option, and it worked as advertised.
> I haven't fully calibrated the V/Octave scaling, but the saw,
> tri and sine look good.
>
> A few observations and a stupid mistake I made:
> 
> 1.  I tested it as a bare board, so I had to clip a jumper
>     from sync-in to -V

Yes, you need to do this. I was looking at an old version of a schematic
which I got online which has the V- hooked up to the sync _out_, instead
of sync in. Had me confused for a while. The latest schematic online seems
to have been fixed. No harm done, I now have 3 (unscaled) VCOs which all 
work nicely. 

The total cost for 3 Tomg VCO boards, 2 Paia VCF boards and all associated
parts, pots/knobs, and fracrack front panels was under $200. Pretty cheap.
They look good too, you can see them at
http://www.cs.brandeis.edu/~aschrock/newpics, look under the "modular"
series of pics, the others are just pics from a show I did. The VCOs are
in the left rack in the middle fracrack. 

Hell, let me know what you think of my modular. It's the first time it's
seen the light of day (web?). 

> 3   By the way, you won't get a square wave until you wire up 
>     the pulse width pot.

Yep, the square out will be silent until you do this. The pulsewidth is
much nice and narrower then my VCO-2's, which the VCO-4's replaced. 

Will get pics up sometime of the 4-input joystick mixer. Am currently
using an analog devices quad VCA chip, which does the trick quite nicely. 

later
Andrew
-| Andrew Schrock | aschrock at cs.brandeis.edu |-