SV: Re: SV: [sdiy] QVCO schemo up

[harrybissell]

Hi Ian

as you guessed, I've been there.  I made my own OTA models and
packaged them as 9 terminal op-amps.  So I can remember the
inputs and outputs by location, but forget the rest of the pinouts.

My first step in an OTA sim is to jack in an external sine wave into
an input and verify the connections to Gm bias etc.

My second step was to add the integrators and cross couple them.

My third step was to wonder why the resulting waveforms were NOT
quadrature sines, but some odd-chaotic thing.

Fourth step was to disconnect the sine wave from step 1 above.

Spice simulations seem to work pretty well for a lot of chaotic apps, you
can do Chua's oscillator etc. At work I can do some of Ian's chaotic stuff.
At home it goes... one nanosecond... two nanosecond... three....

A guy could have more fun watching grass grow :^P

H^) harry

Ian Fritz wrote:

> At 10:12 AM 11/12/05, Anthony Bisset wrote:
> >is the schematic on your web site?  sounds useful.
>
> Unfortunately not.  If you have access to the old ENotes it is in #113 p. 7.
>
> Another use for the quad osc might be to make a chaos generator.  Since it
> is a second order system, this would require driving it from an external
> osc.  You could make a simple one-chip osc with a tuning knob and a knob
> for adjustable coupling to the quad osc.
>
> I should have tried this yesterday, while I still had the circuit
> running.  Maybe Harry could try adding this to his spice
> simulation...Harry?...Yoo Hoo...Harry, old buddy...
>
> Another thing to do would be to try adding another integrator to the quad
> osc to get a 3d order filter, plus a three-phase oscillator, plus a
> self-oscillating chaos generator.  (Switchable back to the original system,
> of course.)
>
> Lots of possibilities.
>
>    Ian (trying out the decature osc today)