[sdiy] MIDI VCO Control - but not CV?

[cheater cheater]

John,
it wasn't review, and was very informative. I know little about
oscillator design :)

Do you know within what boundaries the amplitude should be for a sine
shaper oscillator?


Alternative idea:
what about a circuit analyzing the exact pitch of the signal coming
from the saw/triangle core, and makes up for that in a feedback path?
This could be done digitally while keeping an 'all analog' path.
This could also allow CV modulation to be added: if you have two cores
with the parts placed tightly together (temp. coupled and experiencing
the same magnetics) and very well matched, you could have one core
controlled by 'static' CVs (from keybard etc) while the other core
could accept those static CVs as well as LFO CVs etc. Then analyze the
'static' core and make up to both cores.

Best regards
Damian

On 7/15/08, John Mahoney <jmahoney at gate.net> wrote:
> At 12:20 PM 7/15/2008, cheater cheater wrote:
>
> > What could be done to circumvent the problem of the shapers that
> > create the sines?
> > Cheers
> >
>
>  AFAIK, a sine shaper requires a clean triangle wave of precise amplitude.
> Distortion results if the amplitude is not just right. Part of calibrating a
> VCO involves setting a trimmer or 2 to get the cleanest sine possible.
>
>  Therefore, you need to ensure that the triangle wave has constant amplitude
> and no glitches, which usually means ensuring that the sawtooth wave has
> constant amplitude.
>
>  That's the goal. I've no suggestions on how to achieve it.
>
>  Apologies if that was all review material.
>
>  John
>
>