T.Henry's VCO Deluxe tuning

[Tomy Hudson]

If I understand your problem, this is sort of a chicken and 
egg thing. You need to calibrate the DAC, and PAIA's 
instructions assume you have a calibrated
VCO. To tune a VCO you need a calibrated DAC.

What I did was calibrate the DAC using a voltimeter. Each
octave should increase out of the DAC by one volt (assuming
its not for use w/ linear response VCOs). Once you have the 
DAC tuned. You can use Jim's method to tune the VCOs.

Tomy

scopey at hooked.net wrote:
> 
> thanks for the reply, Jim.  The deluxe VCO circuit in question is
> courtesy of Thomas Henry (Midwest Analog Products-- check the website).
> It's in his book; I highly recommend it, especially if you have some
> spare 3340's.  Heck, I recommend it anyway.  It's really great!
> 
> to be more specific: the VCO circuit has a v/octave trimpot and a high
> frequency trimpot.  the Paia MIDI-cv card has a DAC trimpot, and that's
> it.  Paia's instructions for tuning your VCO with the MIDI converter
> involve:
> 
> 1)play a low note; tune it with a reference by adjusting the trim on the
> VCO
> 2)play a high note(preferably the same note in a higher octave i think);
> tune it to the reference by tweaking the DAC trimpot
> 3)repeat 1 and 2 until the keyboard (MIDI controller) is able to play in
> tune over the entire range.
> 
> i know somebody out there has gone through this....(?)
> 
> -Jeff