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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Postby Harry Dalek » Thu Apr 04, 2013 11:31 pm

After some circuit help from Steve i have this circuit posted here now helping to control my video levels theres also a 100k pot across the diode not shown but after testing looks like i will need a higher value variable resistor the adjustment it to tight at the moment .

I am still finding at higher laser levels if i push it what i think is the corona of the laser is causing the image to be blurred as the drum is picking to much of the uv light up other than raster line .

I may need a mask perhaps .

Heres the laser circuit after Steves circuit i more than likly just need the 10k pot as a fixed lower value resistor the large value pot over the lm311 still seems useful Also the + 5 volt rails should be 12 volt in my drawing.
Attachments
IMG_8547.JPG
Che in room light
IMG_8547.JPG (135.79 KiB) Viewed 8310 times
pwm_1_160.gif
Steves video control circuit used after the last lm741 before the lm311
pwm_1_160.gif (5.43 KiB) Viewed 8310 times
CB.gif
CB.gif (4.71 MiB) Viewed 8310 times
flag2.gif
Another simple NBTV test card used for SSTV
good showing the painting of the image
flag2.gif (3.5 MiB) Viewed 8310 times
P1050092.JPG
P1050092.JPG (258.51 KiB) Viewed 8310 times
P1050187-crop.JPG
the laser circuit as is today
P1050187-crop.JPG (213.36 KiB) Viewed 8303 times
sstv_9.gif
sstv_9.gif (81.82 KiB) Viewed 5867 times
Last edited by Harry Dalek on Sun Apr 09, 2017 11:23 am, 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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Postby AncientBrit » Fri Apr 05, 2013 5:18 pm

Looking very good Harry.

Do you think this principle could be applied to NBTV as well as SSTV or are there fundamental problems in doing so?

Kind regards,

Graham
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Postby Steve Anderson » Fri Apr 05, 2013 6:26 pm

AncientBrit wrote:Do you think this principle could be applied to NBTV as well as SSTV or are there fundamental problems in doing so? Graham

I don't see any reason why not except it does have a very long afterglow which is required for SSTV but not NBTV. It sure would reduce the 'flicker factor' but at the expense of conveying motion, i.e blurring.

With a shorter 'persistence' paint it should be possible.

I've spent quite a bit of time wandering through this thread this morning and have to admire Harry's persistence (pun intended) in getting this to work as well as it does. It is now close on to what you'd expect from a P7 CRT.

Steve A.

Conceptually, imagine Kevin Hadfield's 'carousel' arrangement where the carousel is just a cylinder of fluorescent paint....in other words turn Harry's arrangement on its side and speed it up....
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Postby gary » Fri Apr 05, 2013 6:45 pm

Steve Anderson wrote:I've spent quite a bit of time wandering through this thread this morning and have to admire Harry's persistence (pun intended) in getting this to work as well as it does. It is now close on to what you'd expect from a P7 CRT.
Steve A.


Well said Steve, I bet it looks a whole lot better in real life too.

Just to stir the pot a little, as is my wont, it also shows that replacing the glow drum with a mirror drum, and having the beam played on a flat phosphorescent screen... and now how did those old tektronix displays allow printing to dry silver paper? ;-)
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby AncientBrit » Fri Apr 05, 2013 7:39 pm

Has anyone tried directing a scanning laser beam onto the external face of an unpowered CRT?

This would of course need both X and Y deflection of the laser beam.

Would the phosphor glow or does it only get excited by an electron beam?

EDIT.
For a quick test just use the existing polygon line scan and holding the CRT (in lieu of the phosphor drum) move it sideways and see if a raster is left behind.

Graham
Last edited by AncientBrit on Fri Apr 05, 2013 10:34 pm, edited 1 time in total.
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Postby gary » Fri Apr 05, 2013 7:49 pm

That's a damn good question Graham, and, whatever the answer I would be very interested in the physics of it - electron versus photon. One has rest mass one does not - yet you would think it would be more related to energy carried by one or the other.
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Fri Apr 05, 2013 10:14 pm

AncientBrit wrote:Looking very good Harry.

Do you think this principle could be applied to NBTV as well as SSTV or are there fundamental problems in doing so?

Kind regards,

Graham



Hi Graham oh i already did it some time back with a Octagon and a 4 sided mirror for the horizontal i posted the results
http://www.taswegian.com/NBTV/forum/vie ... ht=polygon

The last few postings are experiments with a glow paint screen and uv laser so it can work,the laser rewrites enough to work but i expect it depends again on the laser levels.

Main reason i came back to the sstv idea i did it the other way around NBTV before this .

I think with projection its a bit gappy with the laser i suppose you need to defocus the laser for a larger image or just view it smaller ..
Attachments
picture_375_146.jpg
NBTV glow paint glass screen with uv laser
picture_375_146.jpg (104.8 KiB) Viewed 8273 times
Last edited by Harry Dalek on Fri Apr 05, 2013 11:37 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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Postby AncientBrit » Fri Apr 05, 2013 10:36 pm

Hi Harry,

re the NBTV experiments I must admit I'd forgotten you'd done that.

Thanks for giving me the link.

Also see my question above re using a non powered CRT,

Cheers,

Graham
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Postby Harry Dalek » Fri Apr 05, 2013 11:02 pm

Steve Anderson wrote:I don't see any reason why not except it does have a very long afterglow which is required for SSTV but not NBTV. It sure would reduce the 'flicker factor' but at the expense of conveying motion, i.e blurring.

With a shorter 'persistence' paint it should be possible.

I've spent quite a bit of time wandering through this thread this morning and have to admire Harry's persistence (pun intended) in getting this to work as well as it does. It is now close on to what you'd expect from a P7 CRT.

Steve A.


I am only sorry i had such a long brake from finishing it to this point it was mainly i had to learn how to get that laser to work and all the different designs ,i had to learn from my mistakes trying to do it with a uv led was pushing it .
As graham was asking about if an nbtv version would work thats where i got it to work so i knew it could work with this older project just a matter of doing it .



Conceptually, imagine Kevin Hadfield's 'carousel' arrangement where the carousel is just a cylinder of fluorescent paint....in other words turn Harry's arrangement on its side and speed it up....



On the NBTV version i painted a photo frame glass the laser lights up both sides of the screen one side reversed other side right way around
The Screen as you see does not have to move but for ths sstv it does help let the glow to die down a bit before the new image is redrawn.
Have to look into Kevins nbtv system .

What i noticed BTW from a past experiment with putting a film negative on the paint and shinning uv... the image left after a while looses the shape and image starts to blur before fading ..it might not so seemed much but it showed me the image detail i could get on the glow paint and that i could rewrite the drum as the image would not last to long.

I would like to test another paint i have before i case ,i know also the glow powder is brighter but i think due to the size of the particles image might not match the finer paints wonder what a drum with both types on would do mmmm

Theres also 12 sec and 32 sec SSTV to try never know 12 should work not much off 8 sec perhaps 32 sec and 72 sec might be pushing it .
Last edited by Harry Dalek on Fri Apr 05, 2013 11:36 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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Postby Harry Dalek » Fri Apr 05, 2013 11:19 pm

AncientBrit wrote:Hi Harry,

re the NBTV experiments I must admit I'd forgotten you'd done that.

Thanks for giving me the link.

Also see my question above re using a non powered CRT,

Cheers,

Graham


HI Graham

Oh you want to know if the Uv laser will light up the phosphor of a CRT...you know i never tried that i have tried to see if the glow paint on the front of a CRT would light up which it didn't perhaps if it was inside the thing ...but i will try i know the uv laser works past clear glass so it would hit the phosphor i will do your experiment :wink:
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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Postby Harry Dalek » Sat Apr 06, 2013 12:16 am

Well said Steve, I bet it looks a whole lot better in real life too.

Just to stir the pot a little, as is my wont, it also shows that replacing the glow drum with a mirror drum, and having the beam played on a flat phosphorescent screen... and now how did those old tektronix displays allow printing to dry silver paper? ;-)


Hi Gary yes it is better to the eye even my bad eyes to the camera ..for some reason in video mode you get poorer light levels with the camera than stills .

Well Flat non moving screen works how about a mirror drum type idea but instead of the 32 mirrors the flat panels of glow paint that would make it easier not having to stick or screw holding mirrors in place ?
You could have square bits of paper painted with glow paint if you wanted to make a angled mirror drum type idea could be a lot easier to do the angles and just a matter of sticking the paper on something flat...as it rotates just point the uv laser at it you would of cause be stuck with the paper size screen unless you used a a large lens wonder if a mirror screw shape glow painted would work too you'd get a better size and the weight of the thing could be dropped using what ever you could paint .
Perhaps this stuff could be used a bit in NBTV for different ideas
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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Postby M3DVQ » Sat Apr 06, 2013 1:15 am

You can definitely "charge up" the phosphor on an un-powered scope with light. I often notice the green glowing square in the dark workshop after I turn off the light on my way out :)

How much intensity/contrast you could get using an appropriate laser is another question of course :)
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Postby AncientBrit » Sat Apr 06, 2013 2:24 am

"Over to Harry", when he has time of course !

Graham
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Postby Harry Dalek » Sat Apr 06, 2013 11:07 am

AncientBrit wrote:"Over to Harry", when he has time of course !

Graham


Bad news with the laser idea Boys i could only test red and uv light lasers i don't have a green handy .

There as you see is nothing photons of these frequencies do not effect it or i should say i saw no after glow as for a screen couldn't be better for NBTV. :wink:

So back to the paints and powders !

I do recall trying it on a fluro and got nothing also.

I am trying something today on the paint side of things to see what a tin with 2 glow paint types do the new paint and glow powder new paint and have try i would like to do a nice glow powder tin but its very hard to get it to stick its never as good as a spray can of the paint if its not even you will get faults uneven lines shadows such.
Attachments
crtuv.gif
UV laser on CRT
crtuv.gif (2.99 MiB) Viewed 8248 times
redlaser.gif
red laser crt test
redlaser.gif (3.5 MiB) Viewed 8248 times
Last edited by Harry Dalek on Sat Apr 06, 2013 4:28 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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Postby Harry Dalek » Sat Apr 06, 2013 12:03 pm

Today i am testing the paints and paint background.
I paint the tin for 2 reasons if you just paint the tin with the label it shows up when the tin glows the other reason is the effect on grays .
I have been using the chrome i want to see if a dark back ground to the glow paint works better.

Also testing the new paint ..waiting for it to dry .
Attachments
P1050194.JPG
how i paint the tins
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P1050196.JPG
old and new paint trial
P1050196.JPG (242.49 KiB) Viewed 8244 times
P1050197.JPG
trying a dark background
P1050197.JPG (235.99 KiB) Viewed 8244 times
P1050198.JPG
first drum painted with new paint
P1050198.JPG (207.96 KiB) Viewed 8244 times
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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