[sdiy] Dual VCO mixing. / first synth DIY project.

[marmot1 at magma.ca]

Electronotes (ENS 98, p.17 -18) shows a circuit for a one volt/oct VCO 
using the 8038. The article states that the circuit behaves well 
over a range of 7 to 8 octaves, but waveform distortion becomes 
signicant below 10 Hz. You should be able to put in a larger timing 
capacitor to get down to lower frequencies before distortion starts. 
The 8038 is not a wonder-chip, IMHO the only good thing about it is 
that it provides a simple means to get a moderately low-distortion 
sine wave. This particular circuit is the only good circuit I have 
seen for it, aside from the simple manual one-pot sine/square generator 
in the app notes.
Regards, Mike

Bill Keys wrote:
> 
> >From: cacofone <pulse8 at goodtimetribe.com>
> >Magnus,
> >Gonna get started on making some VCO's and go from there. Can you suggest a
> >VCO schematic that's versatile and not that terribly hard for a beginner,
> >or is the one there
> >recommended? I'd really like to have at least triangle, square, and I
> >really want sine, even though I know, yes, tri/square are easiest, and
> >perhaps I can add the sine in later after I've implemented square.
> 
> Which makes me think of a question I've been meaning to ask... Does anyone
> know of any VCO (or, if not, LFO) designs (and where the schems might be
> obtained) based on the (old, but still for sale at the 1974 price) Intersil
> 8038 VCO chip? If so, that chip does sine (and triangle and saw, I think)
> and might help both cacofone and I  ;o).
> 
> >Any advice is greatly appreciated.
> >
> Ditto!
> 
> +_+_Yes, honey, I know there are 25 boxes of electronic junk cluttering up
> the attic. They will, one day, magically be transformed into a modular
> synthesizer cluttering up the attic.... www.mp3.com/OriginalSimulacrum _+_+
> 
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