Colour Wheels etc.

[kellys_eye]

Split from this thread:-

https://www.vintage-radio.net/forum/...d.php?t=141400

I seem to recall experiments that had the placement of two monochrome tubes at 90 degrees and coloured glass over them, then the video images extracted from the on-air colour signal (red and blue?) applied accordingly with the combination producing a 'colour' picture - or is my memory failing me?

[dragonser]

Hi,
well it seems it was possible in the USA !
http://www.hawestv.com/mtv_FAQ/colrteBasicFAQ.htm

but it would make a set much larger due to the colour wheel and would need a lot of electronics.

[GrimJosef]

Originally Posted by dragonser

... it seems it was possible in the USA ...

I think Practical Electronics ran a series of articles on converting a black and white set into an 'artistic' sound-to-light display using this technology. The scan circuitry was disconnected and the sound (music) could be used to create linear or Lissajous patterns on the screen which changed colour as the phase between the spinning colour-wheel and the pattern generator electronics varied. I don't recall there being any synch between the two.

Some (most ? all ?) modern domestic digital projectors use an electro-mechanical colour engine I believe.

Cheers,

GJ

[camtechman]

I can't remember the exact year, probably mid 50's or so.

Once a week I used to go to my best mate's house for tea (beans on toast) and also to watch Hop-a-Long Cassidy on their B&W TV (we didn't have a telly until later) and it was during the commercial break that OXO ran a test advert.

They showed a picture of a cow and in a square shape on the side of the cow they flashed different patterns, shapes, moving stripes etc and asked you to write on a postcard what 'Colours' you could see.

The incentive for sending in the postcard was, when colour TV came to Britain you could be the lucky winner of one !

[dseymo1]

There was at least one other demonstration of the flickering colour illusion, on Tomorrow's World.
I think I've mentioned here before an occasion when a significant number of viewers reported having seen an image (a bowl of fruit, I think) in correct colours on their monochrome sets. Never explained as far as I know, but presumably another example of this or a similar effect.

[peter_scott]

Originally Posted by dragonser

Hi,
well it seems it was possible in the USA !
http://www.hawestv.com/mtv_FAQ/colrteBasicFAQ.htm

but it would make a set much larger due to the colour wheel and would need a lot of electronics.

The colour with field sequential is excellent. No convergence or colour purity issues nor any tint problems.

Peter

[paulsherwin]

Originally Posted by dragonser

Hi,
well it seems it was possible in the USA !
http://www.hawestv.com/mtv_FAQ/colrteBasicFAQ.htm

but it would make a set much larger due to the colour wheel and would need a lot of electronics.

I believe some of the Apollo moon landing transmissions used colour wheels.

[Dave Moll]

Yes, one of the best pieces of evidence of this is the footage of a lunar take-off, where the sequential nature of the colour wheel results in a somewhat psychedelic display.

[GrimJosef]

Originally Posted by GrimJosef

I think Practical Electronics ran a series of articles on converting a black and white set into an 'artistic' sound-to-light display using this technology ...

I've tracked down some details here http://videocircuits.blogspot.co.uk/...5/fc-judd.html and a video showing some of the patterns (not with very interesting colours though) here https://vimeo.com/32199187.

Here's the cover of PE Aug 1968 http://www.vintageradio.me.uk/magazi...ics1968Aug.JPG which consists of some screen shots.

Cheers,

GJ

[dseymo1]

I remember reading these articles.
Although as a youngster I was more happy-go-lucky about safety than I am these days, even then it seemed rather a risky contraption in a number of ways! I've always been interested in lightshows and the like, so found it a fascinating idea nevertheless.
I was privileged to witness a demonstration of mechanical field-sequential TV as part of a lecture on colour TV prior to its appearance in this country. My memory is of something noisy and impractically flickery, but then I'm one of those people who can't watch modern DLP projectors either.

[Maarten]

Originally Posted by peter_scott

The colour with field sequential is excellent. No convergence or colour purity issues nor any tint problems.

But some artefacts if you blink your eyes or move your head rapidly. Just try it with any modern projector (which has presumably a higher field frequency so less artefacts).

[peter_scott]

Originally Posted by Maarten

But some artefacts if you blink your eyes or move your head rapidly. Just try it with any modern projector (which has presumably a higher field frequency so less artefacts).

Oh I grant you that, but it's the sheer novelty of seeing respectable colour pictures from such crude technology.

Peter

[Heatercathodeshort]

Peter, all I can say is WOW! John.

[peter_scott]

I took that picture off the screen of the Gray Research Monitor at ETF. Steve McVoy very kindly took quite some time to get it working for me and as Maarten points out, there are artifacts with movement etc but I was very impressed by the results.

http://www.earlytelevision.org/gray_monitor.html

Peter

[Panrock]

Here are the colour wheels I made many years ago for an NBTV project. The other pic shows how they were mounted behind the Nipkow disc for stereoscopic colour.

A separate similar arrangement was needed at the camera.

Steve

[Station X]

I love that ingenious tensioner!

[Panrock]

Tyre inner tube rubber as the 'spring' !

[kellys_eye]

The technique I 'think' I saw used two screens at right angles to each other with a 'deflection' plate (clear glass) in between them. I'm almost certain it was in an old issue of Television Magazine.

A red and green signal were passed straight to each mono tube and the combination produced a 'colour' picture when viewed from the right direction - obviously limiting the number of viewers! - and not full colour by any means (although there may be a better combination of mixing colours to get a suitable image?). It would also have required the reversal of scan for one of the tubes.

Did anyone else see such a project advertised? My wife tells me she knew (as a young child) someone in the Kingussie area (central Scotland) that made a 'colour' TV when they first came out but she doesn't know any more details of the process they used - her comment just reminded me of the example I state above.

[peter_scott]

The two colour system sounds like Baird's.

Peter

[Graham G3ZVT]

Originally Posted by peter_scott

Oh I grant you that, but it's the sheer novelty of seeing respectable colour pictures from such crude technology.

And doubly impressive when you consider that Judy Garland was being photographed by a Technicolor camera loaded with monochrome film.