[sdiy] Oscilloscope question

[Cary Roberts]

>If you don't need great precision, you could "chop" the gain
>between +1 and -1 with a four-quadrant multiplier (or maybe just
>an op amp and a FET ?) and a bipolar square wave.

Several older effects pedal units from Digitech use amplitude modulation of
a square wave to get DC into the DSP via an AC coupled ADC.  I thought it
was pretty slick as it allows for very fast response to user input (pedal
motion in this case) with an otherwise limited slow control processor.

-Cary