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

On Sep 4, 2:55 am, Robert Baer <robertb...@xxxxxxxxxxxx> wrote:
Jan Panteltje wrote:
On a sunny day (Wed, 03 Sep 2008 09:42:57 -0400) it happened Steve
<st...@xxxxxxxxxx> wrote in <205tb41td5tfa5n3esvim42940ikvhh...@xxxxxxx>:

I'm looking for a waveform generator that outputs two sine waves of
the same frequency with 90 degree phase difference (sine and cosine).
I need a variable frequency between 0.05 Hz and 10 Hz.  Is there an
analog design that uses a single potentiometer or perhaps is voltage
controlled ?  Low distortion is not a requirement.

Steve

2 x EPROM sine and cosine lookup table,
4046 VCO variable clock generator,
binary counter on EPROM address lines,
2 x 8 bits wide DA converter, 2 x lowpass.

For a 256 values per sine wave form, your clock should be max 2560 Hz.

   NOT analog.
   Use a ramp oscillator for constant amplitude; one stage generates a
square wave for integrating to the ramp.
   Run a comparitor off the ramp (triangle); that will be 90 degrees WRT
the square wave.
   The 2 square waves can be filtered with a simple 3-stage phase retard
filter.- Hide quoted text -

- Show quoted text -

I was going to sugest a ramp generator also... as a analog
solution..But I din't know if you can build the filter to work at 0.05
Hz! How much distortion can you handle?
George
.

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