Before the first true chorus pedal was built, the only option guitarists had to add some sort of animation to their overall sound was with the Uni-Vibe, which was built in the 1960s by the Univox company. It was actually marketed as a way for guitarists to get that big swooshy sound normally associated with Leslie rotary speakers. However, it didn’t even come close.
But thanks to guitarists like Jimi Hendrix, Stevie Ray Vaughan and Robin Trower, the Uni-Vibe was not only recognized as a superb effect with a unique sound, but the original Uni-Vibe stompboxes became expensive collectors items, since Univox didn’t build that many of them. More recently, Dunlop has come out with a reissue version of the Uni-Vibe.