A televisual curiosity

[Amie]

Quite amazing Steve , thank you. I hadn't realized that common LED's were capable of such bandwidths. I had seen a multiplex analog audio system proposal that used optical filtering to separate individual channels, and wondered if it was ever developed. This seems to be a much more elegant and simple system.

Thanks,
Amie.

[valvekits]

Sorry - Photo didn't load un-rotated.

[valvekits]

I found that the NBTV bunch are very resourceful when it comes to building their own gear and well worth a vist to see what they get up to. it’s a route I most likely would have gone down years ago had I known they existed.
These days I am content to stand back and admire their ingenuity; Karen Orton's video displayed from a compact cassette recorder was interesting. Low resolution when you stood about 2 foot away but as you moved further back the resolution increases before your eyes. I couldn't upload the photo as it want's to rotate clockwise.

Eddie

[Panrock]

Yes, Karen Orton must be undoubtedly the most productive and innovative NBTVer that has ever lived, in terms of the equipment she has dreamed up. Her contribution was vital in getting my 120-line mirror screw to work properly too. The picture on the 'screen' in Eddie's post shows Jeremy Jago, the NBTVA Chairman. He also has been a vital long term influence in the movement.

Still firmly in the realm of "televisual curiosities", I append some more pictures of my past NBTV efforts. 

We see the 'Grosvenor' 30-line colour monitor in its original form, the mechanical colour camera built to drive it, some off-screen results (it seems the mechanical television service was 'commercial'!), and finally - a 45-line colour camera and monitor from the 1990s, which never really worked... but that's merely incidental.   

Steve

[Amie]

I've seen a modern demonstration of the Baird mono, (neon?) Televisor, but those pictures in colour are remarkable, especially considering only thirty lines, what is the light source in that Grosvenor set?

Thanks,
Amie.

[Panrock]

12 "luxeon" LEDs (4 each for red, green and blue) equivalent to several hundred standard bright LEDs. 

They are pulse width modulated', using a circuit design by Steve Anderson (not to be confused with this Steve) and there is 'aperture correction' too.

[Amie]

Thanks!

Amie

[Panrock]

You're welcome. The pictures are actually a lot better when the monitor is fed from a modern electronic source such as a DVD and converter. The use of photomultipliers as the light sensing devices in the camera tended to make the pictures 'peaky' with only a narrow dynamic range. 

Steve

[Panrock]

An update on this ancient thread.

I've come to the end of another time-consuming project, so now have been able to re-jig things in the workshop for a permanent demonstration of the mirror screw. Previously, it was always one hell of a fag to set it all up.

The two illustrations show the screw itself, and (looking in the other direction) the control arrangements, RGB lines-of-light, and the 'hot seat' where you need to sit for the best view. Mirror screw television was never very practical!

So if any of you are ever in the Evesham area and want to see 120-line mechanical colour in action, get in touch for a free demonstration!


Steve

[djrm]

Hi Steve, brililant.

This reminds me of when I was a schoolboy I found a design in a construction book for a flying spot scanner. It had a photo-multiplier tube to pickup the image from a modified TV - our old Decca dual standard with sliding doors iirc.

I have lost the book and no longer have the chassis withthe electronics. I think there about six valves. Has anybody seen a book with a flying spot scanner design, I'd love to see it again.

btw, it never worked very well at all but you could make out a hand in front of the scanning TV.

Kind regards, David.