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

[karl dalen]

--- "JH." <jhaible at debitel.net> skrev:

> > infact this cirquit is nothing more then a variation of the SVF!
> 
> Sure - what else should it be?

Superman! :)

> It's a 2nd order differential equation in the most direct realisation.
> If it's dampded, it's a filter. If it's not, it's an oscillator. The art
> lies
> in keeping it _just_ so undamped, that it oscillates without increasing
> amplitude.

A twin T damped oscillator/filter what's that? A filter or oscillator?
 
> If you make the circuit withtwo slightly different integrator capacitors,
> you'll
> see that as a result either sin or cos output will be of larger amplitude
> than the other.

Yes i know.

> Now make them dramatically different (by removing the diode bias in one
> integrator), and make one of the integrator inputs prone to overdrive at low
> levels (also a side effect of removing diode bias), and a tri / sin
> combination isn't surprising.

OK.
 
> A sine wave with large amplitude and severe slew limiting (because the
> integrator is overdriven) is ...  ... a triangle wave.

OK.

KD