🚀 go-pugleaf

Thanx to all who pointed me at the various VCO/function generator chips.
Exar sent me a wonderful databook full of specs on incredibly sexy toys, and
the end result is a box with 6 XR2206's in it and 8 joysticks and lots
of strange twisting shapes drawn in everyone's favorite 632nm color on the
opposite wall.

The next enhancement for this would be to create some sort of polar-coordinate
display so that I can modulate into R-theta coordinates as well as X-Y.  To
generate the basic circular sweep I need some kind of phase-shift circuit that
will shift my base freq [preferably over a variable range, like from -180 to
+180] without *changing* when I start modulating the amplitude, i.e. changing
the radius.  I essentially want to build whatever is inside a vectorscope.
Is there a simple-ish thing I can do with an op-amp or two to accomplish this?
I have real estate left on the board that's just crying to be used...

_H*