[sdiy] quadrature sine wave oscillator question

[Tim Ressel]

Yo,

I used AD7008 DDS when I needed a multi-phase
oscillator. Expensive, but the phase adjustability
alone was worth the price of admittance.

Of course, it was digital. I'm a digital kind of guy.
Just call me The Big Bit.

(inline comment below)
--- patchell <patchell at silcom.com> wrote:
> Some other
> experiments I did with
> controlling the amplitude of oscilation susgests
> that it is best to get
> the circuit as close to oscilation as posible
> without the AGC, and when
> the AGC is connected in, it has the smallest amount
> of influence.

This is true of all amplifiers (An oscillator is an
amplifier that oscillates). You want to get the
circuit as clean as possble. The more you count on
feedback, the less-well behaved the circuit will be.
There is always lag in the feedback: you are adjusting
what is about to happen based on what just happened.
The is why feed-foreward topology is so cool.

--Tim

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