Re: Dual sine wave generator with variable frequency and 90 degree phase difference

On Sep 7, 8:55 am, whit3rd <whit...@xxxxxxxxx> wrote:
On Sep 6, 5:34 pm, MooseFET <kensm...@xxxxxxxxx> wrote:



On Sep 7, 6:20 am, whit3rd <whit...@xxxxxxxxx> wrote:

On Sep 6, 12:50 am, MooseFET <kensm...@xxxxxxxxx> wrote:

On Sep 6, 10:01 am, whit3rd <whit...@xxxxxxxxx> wrote:

On Sep 5, 9:14 am, MooseFET <kensm...@xxxxxxxxx> wrote:

The phase shift oscillator is a bad idea
It's not that bad... the only requirement is four matched C values.
The OP wants 0.05Hz to 10Hz. Over that range you need the ability to
adjust more than two sections of the phase shifter if you want to work
with a near constant gain.

Of course. These are TRANSCONDUCTANCE AMPS with
current program pins, all cascaded. The four sections
all change R_output together. A single pot changes four sections
of the RC phase shift all in unison.

That is a lot more parts to do it that way. You need 4 CA3080s for
this version and only 2 for the state variable version.

Well, not CA3080 (they're obsolete); dual OTAs (NJM13700) are $0.68
each at Mouser. If it takes two, I can afford that.

It is a moral outrage to use more parts than needed :>
.

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