awalker@topaz.rutgers.edu (*Hobbit*) (05/25/88)
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*