[sdiy] current question

[harrybissell at wowway.com]

The Aries 317 (or was it 314?) VCO used a triangle core, with
a second current source feeding a capactior to make a sawtooth wave, which was
hard sync'd to the triangle core. Worked well with some slight amplitude
imperfections.

H^) harry


On Thu, 26 Jul 2007 13:54:17 -0700, Gene Stopp wrote
> If the first core is a tri-square core (integrator/comparator) you 
> can do this to get a half-frequency triangle waveform:
> 
> Drive a flip-flop with the square wave to get a sub-octave square 
> wave Use this square wave to invert/don't invert the triangle wave 
> Sum part of this square wave into the resulting wave to get a 
> suboctave triangle
> 
> I submitted this to EN long ago (actually it was thru my friend Iggy 
> Foulke who was the actual subscriber at the time)
> 
> - Gene
> 
> At 03:04 PM 7/26/2007, harrybissell at wowway.com wrote:
> 
> >I'm imagining what you might be trying to do and can't think
> >of a real simple way
> 
> Yeah, I imagine that what I'm trying to do matters a great deal. :-) 
> OK. I was trying not to go there -- better to test one's possibly 
> dumb ideas in private! -- but my idea is this:
> 
> Can we make a "dual core" VCO? (To borrow a term from modern 
> microprocessors.) One core would behave normally, while the second 
> would run at half the rate of the first. The second core would be 
> hard synched to every other cycle of the first core so that it would 
> run at exactly half the rate. The goal is to produce a suboctave 
> output that's not a square wave.
> 
> Another way to put this is that the second core is a relaxation 
> oscillator that's reset by a square wave suboctave of the main core.
> 
> Heck, this doesn't even need a second current source, does it? The 
> second core can simply charge to twice the voltage of the primary core.
> 
> Is this as trivial as it seems to be?
> --
> john
> 
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Harry Bissell & Nora Abdullah 4eva