From obxwindsurf@yahoo.com Wed Oct 01 15:27:30 2003
Subject:Re: Solid State scanner project

Steffan,

If I had an A-100 I would be figuring out how to get it into my
custom-built Leslie right now so I can understand how it made the CV
project obsolete :)

I did a little bit of design work today and as it turns out, I can
create an op-amp sine wave oscillator trimmed to the correct
frequency, and run it through a zero-cross comparator to get the
squarewave to clock the muxes. If I run the sine wave through a
precision half wave rectifier, and also invert the sine wave and run
the inverted version through a precision half wave rectifier I have
two HWR sinewaves 180 degrees out of phase. Now if I add a little
negative bias to the HWRs and shift the result up to zero volts,
voila! I have a smooth pure-frequency LFO waveform with transfer
overlap just like the rotary scanner's rotor and plate groups. By
making the negative bias and the level shift adjustable, I can
control the amount of overlap, and if I futz with the design a
little while longer, I can probably get the overlap trimmer to be a
single pot rather than two (which currently are independent of each
other).

Regards,
Kevin

> Sounds interesting.
>
> Steffan
>
> [Non-text portions of this message have been removed]