[sdiy] Arp odyssey VCO...

[Tim Parkhurst]

On 2/23/07, jean-pierre.desrochers at ville.quebec.qc.ca
<jean-pierre.desrochers at ville.quebec.qc.ca> wrote:
>
> I was looking at the ARP Odyssey VCO schematics
> today and was thinking of its simplicity and yet
> its wide linearity.. easily 6-8 octaves.
> I tested it on my version I (Odyssey 2800).
> http://www.physicsenterprises.andrews.edu/diy_archive/manuals/arp/odyssey/od
> y_30.gif
> Should it still be considered even with today's
> comparator/fet IC's. Just replacing the few needed
> parts with new chips and good caps could be a real
> good choice for a modular VCO...?
> Just my opinion.
>
> Jean-Pierre Destrochers
>

Hi Jean-Pierre,

With excellent tracking and stability in the original design, why
bother changing anything? The ARP temperature-compensated VCOs are
some of the best around, and like you say, they're relatively simple.
About the hardest part of building them is matching some transistors,
and tracking down the 1.87K tempcos (ask on the list, I'm sure someone
can sell you a few). You might want to think about substituting some
modern matched tranny pairs (LM394, MAT02, etc, etc.) for ease of part
sourcing, but that's about the only thing I'd change. Of course, use
good quality polystyrene caps and 1% metal film resistors, but
basically, why mess with a good design?


Tim (basically a good design, just waiting for the right parts) Servo
-- 
"Imagination is more important than knowledge." - Albert Einstein