thinmint:
I want to use an arduino, either a mega or an UNO R3, to make both signals at the same time. I know a mechanical relay would not be capable of running the necessary frequencies (0 - 100khz-ish), so how would I do this? Transistors?
Better use MOSFETs, they're more efficient in switching, faster, too. Provides more power if you need it, aswell.
Good luck on the project! Quite ambitious, but FUN! Post some pictures!