Can't agree more.i_build_stuff said:I think the mechanical issues with that will be harder than the electrical ones.
What I would do is put all the electronics inside the cylinder, and feed it video through a vertical antenna running up the center (so the received signal doesn't change with angle). Then your electronics can read off a line of pixels to the LEDs on each angular step.
A hall effect sensor probably won't be fast enough to provide accurate synchronization (that thing will have to spin really fast), but you could use some kind of optical detection. Maybe one or more LED's on the outside, at the top or bottom, with a sensor spinning around on the cylinder. Then you could use a PLL with frequency division to derive a clock.
Dan East said:Sure, I'd love to see some pictures. Sounds like you'll be moving onto some hi resolution stuff soon.
Dan East
ChriX said:Do you think there will be any advantage to using separate LEDs for each colour rather than RGB LEDs?
Dan East said:My Yaesu VX-7R has an RGB LED that you can program for any 24 bit color, and with low intensity colors you can clearly see the individual emitters in the LED. With bright colors it all seems to blend together better.
i_build_stuff said:What resolution are you going for?
I forget what the res on those HD-DVD's is, but it was somewhere around 2000 x 1000. If you had that in 24 bit color, with 3 channels, at 25 frames/sec, it would take about 3.6GBit / sec to transmit (or 1.8GHz of analog BW). That would be do-able with a round waveguide running up the center, in a mode where there is no current along its axis (I think the TE modes are like that).
Otherwise, you might consider using the brushes, but not actually making contact (instead, capacitively couple the signal in through an outer ring that's very close to the inner ring). Unless the video will be digital (with error correction), regular brushes will probably be too noisy.
This might also be a good time to think about video compression...
ChriX said:Looks like it is coming along well, keep us updated!
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