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

[karl dalen]

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

> > I agree with your result of removing the diode bias. With both removed, I
> get
> > rounded triangles. I did not try just ~one~ removed.
> 
> You certainly know that, but when removing the diode current, and not using
> much smaller resistors from inputs to GND, you get much more gain,
> and overdrive the OTA. This explains the triangle stuff when one diode
> current
> is removed: you get vastly different integrator time constants.

I have to audit entierly my shall we say "screwed up delightment"
of this cirquit, infact this cirquit is nothing more then a variation 
of the SVF!

Very similar to the CEM3350.

But i have doubth that the source of the triangle syndrome are caused by the
diode biasing because you can repalce the zener folder into a single diode
folder stage and the triangle dissapers, only sine are possible no matter 
whether you bias the stages or not. 
So i wonder how can you shape an sine into a triangle with one OTA?
Wouldent that take more then a feedback loop or cross coupled stages?

Uh, but my scope tells me the reverse??? How come, Im confused!

KD