I'm contemplating (again) a mechanical-scanning display. All homemade displays I've seen so far are fairly lame because they only show time or some pre-programmed text and stored animations. If I'm to make a display, it's going to be able to show full-motion video. Since the damn thing is going to spin at some 5000rpm, the primary problem is of course the data link. Power can be delivered by rails and filtered, filtering a data link is a bad idea.
I don't like brute force solutions like putting a wifi-enabled/mpeg4-playing linux router on the spinning part, even though it could be very funny.
I'm thinking about using a very short range optical link between the static and rotating parts. The transmitting side could flood a pretty large area, so even if the receiver photodiode has to be off-centre it will still be getting the stream. But I never did anything like that, never did any data transmission lines actually. What is the maximum possible BW with a led/photodiode combo? Modulation types recommended? Something like SPDIF, digital stream with self-clocking NRZ: should work but the receiver could be not very simple and, most importantly, I don't want to spend years on decoding/ERC code. Or I could actually just make an analog optical AM link for composite video: should be easy-peasy but if light source/receiver get misaligned I'll get funny patterns.. Analog FM-modulated composite perhaps then? What's a few MHz for an IR LED?