Rooting in the junk drawer for a 1A fuse this morning and came up with a colour filter wheel off an old slide projector, which put me on to Peter Goldmark. His scheme was a disc of red, green and blue filters spinning in front of the camera tube, and a second disc spinning in front of the picture tube in your front room, locked in step with the first. Your eye does the mixing. No colour in the signal at all, just three greyscale pictures taking turns. The FCC blessed it in 1950 as the first commercial colour standard in the States.
Here's the clever bit: all the colour engineering sits in the mechanical parts, so there's almost nothing to go wrong in the electronics. The trouble was the timing didn't match the 525-line sets people already owned, so a few million black-and-white receivers in living rooms got nothing out of it. Broadcasts started in the summer of '51 and were over by that October; CBS pulled the standard in 1953. I never saw one working. I'd have liked to hear the motor come up to speed.
Wendell, the cinema got there first and just as mechanically — Kinemacolor, around 1908, ran a red-and-green filter disc in front of the camera and another in the projector, and you could hear that one come up to speed from the fourth row. As for CBS in '51, I gather the first commercial broadcast went out to a handful of sets that could actually show it. Lovely picture, almost no audience.
Wendell, the geometry of it kills me — the disc has to be wider than the screen, so a big set means a spinning colour wheel about the size of a bicycle wheel in your sitting room. Tracking stars I've used filter wheels maybe the width of a jar lid, and those are loud enough.