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Old 10th Mar 2018, 6:02 pm   #1
Panrock
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Default 30-lines in colour

I crave your indulgence. Now for something a little different.

Well, it is television... sort of! Obviously this sort of thing really belongs on the NBTVA Forum. Nevertheless I thought it might be of interest to some here.

Having done with the 120-line Mirror Screw, this year I've gone back to 30-lines. So I've just finished rebuilding my old Nipkow disc based colour monitor to give horizontal scan. Pictures attached.

Steve
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Old 10th Mar 2018, 7:04 pm   #2
ianm
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Default Re: 30-lines in colour

Fantastic results. Love it!
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Regards

Ian McLaughlin, BVWS member
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Old 10th Mar 2018, 7:49 pm   #3
peter_scott
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Default Re: 30-lines in colour

It is really very impressive. If Baird had used colour at an early stage of development he might have gained greater sway with his 30 line transmissions.

Peter
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Old 10th Mar 2018, 8:15 pm   #4
Panrock
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Default Re: 30-lines in colour

Baird demonstrated colour in 1928, using a field sequential system; e.g. http://www.earlytelevision.org/baird...cal_color.html

What he didn't have were modern Luxeon LEDs for modulated coloured light sources. I believe he used gas discharge tubes. Since the single hole-at-a-time of the Nipkow Disc lets very little of the light through from behind, having a really brilliant light source helps greatly with obtaining a convincing result.

Steve
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Old 10th Mar 2018, 8:53 pm   #5
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Default Re: 30-lines in colour

Steve,
Wow! That is really something, what a beautiful machine, fantastic images.
Hugo.
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Old 10th Mar 2018, 10:43 pm   #6
Panrock
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Default Re: 30-lines in colour

Thanks Hugo. I have the feeling that if you were to ever add NBTV to your range of activities, then we'd really see how it should be done!

Steve
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Old 10th Mar 2018, 10:49 pm   #7
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Default Re: 30-lines in colour

Steve, those images are incredible. Somewhere - far, far away in another invisible parallel universe, perhaps - the nebulous glow of energy that we would like to think of as John Logie-Baird's spirit is nodding approval
Guy
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Old 11th Mar 2018, 10:59 am   #8
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Default Re: 30-lines in colour

Makes one wonder what can perhaps be done with a beefy 3-colour led, and some fairly simple (by today's standards) logic circuitry? Tony.
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Old 11th Mar 2018, 11:14 am   #9
Aerodyne
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Default Re: 30-lines in colour

What a great result. I am in awe of your skill.

Tony
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Old 11th Mar 2018, 11:47 am   #10
Panrock
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Default Re: 30-lines in colour

Thanks Tony, but of course, judging from your books, the reality is the other way round!

This televisor is actually rather bloated and ugly, with 'gratuitous' shoulders added for mere effect. But then that's always been my sort of thing. It's also extremely heavy!

Steve

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Old 11th Mar 2018, 4:32 pm   #11
rogerdup
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Default Re: 30-lines in colour

Congratulations for your nice results. I am been myself involved in mechanical television time ago and got excellent results with my large nipkow disc for 60 lines prototype. Hereafter I put photo of this machine I sold time ago to a museum in Norway.
The ETF web site kindly still host my mechanical workshop machines.
At one time I have been proud to submit to Malcom Baird my reproduction of John Baird's Televisor . He like very much..
Best regards,
Roger
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Old 11th Mar 2018, 4:48 pm   #12
Panrock
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Default Re: 30-lines in colour

Welcome Roger! Your many achievements in NBTV are well known and few of us will ever be able to match your knowledge or standard of construction.

You will see my mirror screw has much better definition than the 30-line pictures I have shown above. See https://www.youtube.com/watch?v=ELk4DmqwNms

All the best,

Steve
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Old 11th Mar 2018, 5:57 pm   #13
rogerdup
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Default Re: 30-lines in colour

I am impressed by your mirror screw color images. You did a real excellent job!
On myself, I spent lot of time trying to get acceptable results with my 60 lines mirror screw prototype.Unfortunately, I was lacking of appropriate tools to make the accurate mirrors adjustment. That is the most critical thing to do with that machine.
Here after photo of my 60 lines mirror screw.
Keep doing the good work Steve !
Best regards,
Roger
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Old 11th Mar 2018, 6:10 pm   #14
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Default Re: 30-lines in colour

Yes, critical adjustment of the mirror slat angles is a difficult problem. For my 60-line screw, I made a special tool from a long-jawed mole grip (with screw adjustment) to 'click' adjacent slats into the correct position with respect to each other.

For 120-lines, even this wasn't sufficient. So I used an electronic correction box very kindly developed and constructed by Karen O.

Steve
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Old 12th Mar 2018, 12:54 pm   #15
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Default Re: 30-lines in colour

At the risk of repeating myself, the ability of the members of this forum never ceases to amaze and, frankly, rather humble me. I don't think I've ever been in danger of becoming swollen headed but should the risk arise, I'd only need to look at the contributions of Steve, Roger and others to come back down to reality with a bump.
The video link is very addictive...

Tony
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Old 12th Mar 2018, 2:38 pm   #16
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Default Re: 30-lines in colour

It has been shown on this forum before, but if the mods will permit, it might be useful to describe what you're actually seeing in that video, for the device producing the picture is whizzing round and effectively invisible. A close-up of how it is constructed is attached here.

The mirror screw consists of a stack of slats bearing reflective edges. It's the edges that do the actual work. Each one handles one line of the picture. The slats are stacked so each one sits at a slight angle with respect to its neighbours. This results in a staggered arrangement, looking like a large corkscrew.

When a 'line of light', perpendicular to the slats, is seen reflected in one of them - a single spot of light is the result. Rotating this 'screw' of staggered slats then results in the spot of light tracing out a raster. Modulate the light with video, synchronise the screw's motion to the video source, and you get a picture!

When watching television on a working mirror screw, you look directly at it and the television picture looks as if it lies deep within, as far behind the screw as the line of light is in front. This effect is actually quite pleasant. It certainly is a different way of watching television!

Steve
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Old 13th Mar 2018, 12:02 pm   #17
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Default Re: 30-lines in colour

One difficulty is also to find a linear source to light equally each mirror edge.
After various try I finally use a led ramp with some plastic rod as magnifier.
The second photo show a prototype with tri-color (rgb) leds and monocolor to choose for, by turning the led assembly.
R.D.
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Old 13th Mar 2018, 12:42 pm   #18
Panrock
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Default Re: 30-lines in colour

Yes Roger, I too used lines of LEDs.

For colour, I originally used a frosted acrylic mixing rod. Later on, I was able to dispense with this and used adjacent rows of bare red, green and blue LEDs, with special lenticular film to smear the separate LED 'dots' into true lines. This was a much more efficient arrangement and the colour convergence between the lines was handled by Karen O's Timing Corrector.

The LED lines are now so bright they are probably dangerous to look at directly.

Steve
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Old 13th Mar 2018, 3:06 pm   #19
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Default Re: 30-lines in colour

Interesting, good work Steve!
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