Mechanical SSTV Steps

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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Re: Mechanical SSTV Steps

Postby Harry Dalek » Fri Nov 17, 2017 10:28 am

Robonz wrote:Hi Harry, that's good advice

I made 2 watt laser scanning module which is mounted in my lounge to make a blue sky effect, also a half watt red heavily defocused on to a mirror ball. It uses the same laser polygon mirror. It looks great when I run my smoke machine. It's so powerful it will burn the wall if I let it stop. I programmed the laser to turn off if the mirror drops below a certain speed for safety. I have built quite a few laser projects in the past. I need to get a better picture for you, but you get the idea.

[url]laser_sky.jpg[/url]

And here is one of my robots with a custom camera/laser range finder. I blew a few lasers making that one. It can measure distance in stereo 400 times a second
https://www.youtube.com/watch?v=5SS7I66ut9w


Thats good Keith your familiar with lasers ....you have one up on me i have never tried one in the watt range ...your also braver than me with a laser light show these things are fun but do scare me they are one toy we NBTVer's need to be careful with ...
I would think one in the watt range full power would be too high for a SSTV it might burn the paint ...in my posts pages back there are 2 mechanical printer type SSTV's 73 magazine i think similar idea some thing that came to my attention was heat sensitive paint my daughter had a few little rulers you hold them for a bit and they change colour ...i am sure if you could paint a tin in this and had a laser powerful enough it would so the same as a UV laser on phosphorescent paint ..higher still burn a hard copied of the scan on paper ...they sort of did this with heat sensitive paper and a heated up stylus in one of those early SSTV Fax mechanical systems ...i have also seen heat sensitive sand and they have painted an image on with the sand in a glass tube .
On the scanning methods ....
I always wanted to also do this on a flat screen i tried it only with sstv with a uv led and focused it ...the scan works it was before i got the lasers the framing fly back to start position is not as neat as a rotating drum at the time as i had the led on a a dvd laser position rack doing the framing side of it up and down ..a 2 drum thin line mirror say polygon and a thicker framing mirror drum would do the same like a mechanical CRT so you could do it on the flat ...you would just have to wait a touch for the last image to defocus .
ON this also doing some research i read that a red laser would decharge the phosphorescent glow like a rubber but it never saw this effect when i tried may be the laser level something to do with it don't know ..if you still go the drum by the time it rotated back you have a clear enough screen to paint another picture any case .
I am pretty sure also that this method of a mechanical SSTV can beat the P7 CRT at least to a 12 second scan there is this in the chroma pix sstv program .
Last edited by Harry Dalek on Fri Nov 17, 2017 5:46 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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Re: Mechanical SSTV Steps

Postby Robonz » Fri Nov 17, 2017 4:31 pm

Hi Harry

Thanks for commenting back , I always enjoy reading your responses.

The thermal idea is interesting but thinking about this you would get a lot of defocus as the heat would spread. Even with glow paint the focus has the issue of the paper you painted on, leaks light causing defocus. I was thinking if aluminum foil "backer" was use then it might give a sharper image as it will only reflect and it will not diffuse. I was also wondering what retro-reflective tape would do as the backing.

The other thing that really interests me is "phosphor quenching". Check out this video
https://www.youtube.com/watch?v=jPg3dU4YWVc

It seems that "some" phosphors will quench really well with IR light. I tried IR light on my "aqua" phosphor and it did not work. I need to find a phosphor that does quench well as I think it would look very cool if you could blank the image as it finishes ready for the next image. Any ideas? I found 4 phosphors easy to buy. just search "alpha industries glow in the dark powder" but which one will quench. I guess I should buy all samples to test.

Cheers
Keith
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Re: Mechanical SSTV Steps

Postby Harry Dalek » Fri Nov 17, 2017 6:25 pm

Robonz wrote:Hi Harry

Thanks for commenting back , I always enjoy reading your responses.


Your really the first here to give it a go that i know of apart from me so with your construction stills it will do it justice .

The thermal idea is interesting but thinking about this you would get a lot of defocus as the heat would spread.


I don't think it would be any worse than glow paint as focusing is the key focus to a point in one area as with glow paint it will defocus in time very quickly as far as spreading the heat thermal paper doesn't an experiment if you put say something warm onit with a shape remove the shape if you see that shape it will work because one area is warm other not so it doesn't spread it ..the ruler i have somewhere would be a good little screen to test !

Even with glow paint the focus has the issue of the paper you painted on, leaks light causing defocus. I was thinking if aluminum foil "backer" was use then it might give a sharper image as it will only reflect and it will not diffuse. I was also wondering what retro-reflective tape would do as the backing.


If you charge the paint up to a point with uv light its in focus very fine after some seconds this point does defocus which is what you want so you can paint a new image... when i started the project i was told it was not possible as this stuff glows all night when charged it does but it also can not keep the throwing out photons to the same extent degree as first charged seconds ago so the drum glows but it is still possible to recharge it to a higher level and the project shows it does work you can paint and repaint SSTV images ...An early experiment was place a slide over say paper painted in the glow paint and shine a uv light over the slide and remove slide depending on how long you charged the paint with uv light the image would first be in focus and defocus more slowly depending on the time of charge .
viewtopic.php?f=23&t=1318&start=60

The other thing that really interests me is "phosphor quenching". Check out this video
https://www.youtube.com/watch?v=jPg3dU4YWVc


youtu.be/jPg3dU4YWVc

Arrr thats what i was saying about the red laser as a rubber for the phosphorescent paint no wonder it didn't work when i tried its a IR laser needed ..that would be good on the other side of the drum to wipe out the glow from paint..... trust it to be explained in a Jeri Ellsworth video i missed!


It seems that "some" phosphors will quench really well with IR light. I tried IR light on my "aqua" phosphor and it did not work. I need to find a phosphor that does quench well as I think it would look very cool if you could blank the image as it finishes ready for the next image. Any ideas? I found 4 phosphors easy to buy. just search "alpha industries glow in the dark powder" but which one will quench. I guess I should buy all samples to test.

Cheers
Keith


Yes its a good idea i would of used it if i had known.
i would think it would give an image better contrast than a glow drum without it ...i would scan the IR laser behind drum perhaps a touch defocued if that will be enough and give your self a clean screen for the coming scans its a very good idea....I didn't know it was in the infra red range needed what i read was it was a red laser there your go now i know thanks to your interest ! Now IR is heat wavelength really so try some thing that throws off heat should in theory give the same result !~get a hair dryer !
BTW this idea the glow drum could work in reverse just IR laser and charge the drum up from behind some uv leds even daylight suns UV could do it and the ir would wipe areas not wanted in the image ...
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Harry Dalek
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