thyristor VCO

[gstopp at fibermux.com]

     I've played with the Electronotes CA3140/FET VCO over the weekend (as 
     part of my experiments with my new circuit board design) and it's 
     fantastic. Really excellent tracking and range. The sawtooth reset 
     time is in the nanoseconds range so the sawtooth retains its waveshape 
     well above 100 kHz, and no high-frequency track adjustment is needed.
     
     It's got a very low parts count as well. I admit I haven't tried the 
     thyristor approach yet. Isn't that the method used in the National App 
     Note #299 VCO, BTW?
     
     - Gene


______________________________ Reply Separator _________________________________
Subject: thyristor VCO
Author:  Haible_Juergen#Tel2743 <HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de>
at ccrelayout
Date:    4/26/96 11:45 AM


Hi!
     
I was wondering what experience you have with these
VCOs that use circuits similar to thyristors for capacitor 
discharge. Thyristors being built from at least one
npn and one pnp transistor, like in Korg Polysix or 
MS-20.
At the first glance this would be the most economic design 
method for polyphonic stuff, as it has the least component count 
by far!
I have not built one of these myself yet, so I'd like to know 
what pitfalls are there to avoid.
     
Any thoughts?
     
JH.