[sdiy] Additive VCO

[Theo]

I was thinking high speed vco then dividers, then square to tri then tri to
sine.
Think diode clip should be ok for the tri to sine.
And the divider train could be based on 4017 with divide by 2 (gates) on its
outputs to get square.
This gives odd and even partials locked in phase.
On the down side, no detune between the partials.

Cheers
Theo



----- Original Message -----
From: Ken Stone <sasami at hotkey.net.au>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Monday, March 08, 2004 3:24 AM
Subject: Re: [sdiy] Additive VCO


Maybe start with a triangle oscillator, then rectify, and amplify to get the
second, do again for the fourth etc. Feed the triangles into triangle to
sine converters, and you have a number of your waves already nicely phase
locked.
Of course for third, fifth etc, you'd need to get creative.

Ken

>Hi everyone,
>
>I'm trying to design an additive-VCO, there aren't too many around, and
>that's why I would like to at least try it myself.
>My initial idea is by having one expo-converter, having the output devided
>over several Opamp-adders (to create the harmonic-offset). Those
Opamp-adders
>have 2 inputs each then, one with the CVin, and one with the offset
voltage.
>Each of those opamp outputs then go to seperate Sine-VCO's, one sine for
>each opamp-output.
>Then finaly mixing all the signals together, and that should be it.
>The things I'm troubling with though, is how many harmonics (i.e.
>Sine-VCO's) should I have at least to create a decent Additive VCO? I was
thinking of
>about 16 Sine-VCO's.
>Another thing that popped up is: How "correct" do they have to be?
>I can assume that if you want to create fairly true additive waves, with
>Fourier in mind, they have to be pretty accurate, increasingly with the
>harmonic-number probably.. But I wouldn't know how this would be in "real
life".
>I hope anybody could help me, does anybody maby already have some
experience
>in this?.
>
>Thanks, cheers,
>Michiel
>
>--
>+++ NEU bei GMX und erstmalig in Deutschland: TÜV-geprüfter Virenschutz +++
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>
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or ken at cgs.synth.net
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