I always wondered what exactly was in phase shifters and phlangers, but never bothered to open one up or look at a schematic to see. It isn't just a device that shifts phase of the entire audio band by a fixed amount, 'cause that wouldn't be audible. It sounds like it shifts a certain frequency range and then varies the shifted amount in relation to the rest of the band so that the interaction becomes audible.

Undoubtedly you guys know the answer. Just out of curiosity, what kinds of circuits are used in those things?