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 Steve Anderson » Tue Jun 14, 2011 7:20 pm

I'm astounded by the effort quite a number have put into this thread.

For years I have had mechanical SSTV on a back-burner, though only in my head. Harry (especially), well done. Other contributors also muchly thanked.

I had always intended to attack this from the 'camera' end first, but my thoughts and scribbles on paper have come to nothing more than just that.

With my impending return to the UK about a week away and my workshop effectively mothballed I'm not going to able to add much here.

Thanks again to those that can.

Interested? You bet!

Steve A.
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Postby Harry Dalek » Tue Jun 14, 2011 10:36 pm

Steve Anderson wrote:I'm astounded by the effort quite a number have put into this thread.

For years I have had mechanical SSTV on a back-burner, though only in my head. Harry (especially), well done. Other contributors also muchly thanked.

I had always intended to attack this from the 'camera' end first, but my thoughts and scribbles on paper have come to nothing more than just that.

With my impending return to the UK about a week away and my workshop effectively mothballed I'm not going to able to add much here.

Thanks again to those that can.

Interested? You bet!

Steve A.

Hi Steve

good to see your back till the next trip !!!!i was thinking you might enjoy the schematics sstv monitors from the 73 magazine i really like the p7 8 sec monitors sort of lost it for me when it was dropped for ic's scan converting ....

I know the qsl magazine has a few monitors but the pdf's are not free for download and they don't seem to use pay pal which is a pain for me .

Thats interesting you had wanted to make one as you saw in my posts it had been done in the 70s via paper .
I had not thought of a camera mainly the lazy factor since i have a signal
via pc .
Was your monitor idea via paper ?
Since doing this and reading viewing stuff i think a good way to do it still using the glow paint ink what ever on paper rotating flat via 2 rollers just going around in a circle like a slow belt sander ...8 sec speed .
For the 16hz horizontal i am thinking of a light screw helix this is just above the the paper with a mask slot between it and the paper so as the horizontal drum rotates ,under the slot the a light dot is just seen moving across the paper painting light lines onit....nice and close just another idea thinking about it .

I now have my 50mw blue laser i tried it on the glow paint it works think it is close to the frequency the paint glows, my laser running at 405nm...i think its close to uv ...

OH and i also have laser gloggles now feel a bit safer playing with them .

BTW they do sell uv luxeons which is interesting .

Since i have this now i will do some testing but i really would like the laser dot smaller its a bit thick for 120 lines about spot on for nbtv but .

I might as well try it in the rotating drum and see how well it does with out the lens and just using the rotating drum dvd lens...we will see.

With the experiments i have done prelaser the light +lens or hole with light behind it needs to be close to the glow paint surface or you loose the effect of a long Persistence Glow....with the laser i hope to over come this distance from the paint problem .and we are talking getting past a mm or so .

I have been side tracked of late putting my laser luxeon pwm circuit in a case and putting a motor control board in another case ,i will get back to the tests soon.

Have you noticed my Avatar picture it will never work the people at secret life of machines got it the wrong way around.
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Postby Steve Anderson » Wed Jun 15, 2011 4:27 pm

I must admit I had not considered a mechanical SSTV monitor because as you say, the P7 phosphor was the answer...pre computer age.

At that time I had no way of generating a 'real' picture, either done live or some form of scanning a photo...much like a fax machine. Simple patterns like bars or grille was just a few power-guzzling (7400 original type) logic chips. But that's not a picture to me.

I did a lot of sketches and spent hours/days on this and nothing ever came of it. I was still a student, therefore impoverished* and still had the chore of studying to do.

Late last year I started working on something akin to this but it wouldn't have generated a true waveform, either SSTV or NBTV on it's own. It still required some number-chunching by a small micro, though not a PC.

It was based on a standard 33RPM turntable...yes I still have one! This 33RPM provided the horizontal scan. Only about 30-40 degrees would have been used as the field of view. So most of the time during rotation would have been wasted.

The vertical scan was to be provided by some means of 'nodding' the sensor assembly slowly in one direction then a quicker retrace. This was to be for conventional top-left, bottom right scanning...as per SSTV.

Where I fell foul was the sensor assembly. I wanted to do this without any glassware of the optical vatiety, that is a pin-hole arrangement.

This is where I spent most of my effort and quite simply although I got a video waveform it was far too noisey. A PMT could well have done the job but as this whole thing was designed to sit on a rotating turntable with no slip-rings for signal or power that idea was shelved. Semis and on-board batteries it had to be. Signal out was by a vertical on-axis IR LED/photodetector link.

I'm sure it can be done but when I reached the point above the evil of work in the UK loomed, so that was that! I may go back to it later in the year but conceed that a lens IS required. At least in the manner I was trying to do it.

Steve A.

*I'm still impoverished, nothing changes!
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Postby Harry Dalek » Wed Jun 15, 2011 9:36 pm

Steve Anderson wrote:I must admit I had not considered a mechanical SSTV monitor because as you say, the P7 phosphor was the answer...pre computer age.

At that time I had no way of generating a 'real' picture, either done live or some form of scanning a photo...much like a fax machine. Simple patterns like bars or grille was just a few power-guzzling (7400 original type) logic chips. But that's not a picture to me.

I did a lot of sketches and spent hours/days on this and nothing ever came of it. I was still a student, therefore impoverished* and still had the chore of studying to do.

Late last year I started working on something akin to this but it wouldn't have generated a true waveform, either SSTV or NBTV on it's own. It still required some number-chunching by a small micro, though not a PC.

It was based on a standard 33RPM turntable...yes I still have one! This 33RPM provided the horizontal scan. Only about 30-40 degrees would have been used as the field of view. So most of the time during rotation would have been wasted.

The vertical scan was to be provided by some means of 'nodding' the sensor assembly slowly in one direction then a quicker retrace. This was to be for conventional top-left, bottom right scanning...as per SSTV.

Where I fell foul was the sensor assembly. I wanted to do this without any glassware of the optical vatiety, that is a pin-hole arrangement.

This is where I spent most of my effort and quite simply although I got a video waveform it was far too noisey. A PMT could well have done the job but as this whole thing was designed to sit on a rotating turntable with no slip-rings for signal or power that idea was shelved. Semis and on-board batteries it had to be. Signal out was by a vertical on-axis IR LED/photodetector link.

I'm sure it can be done but when I reached the point above the evil of work in the UK loomed, so that was that! I may go back to it later in the year but conceed that a lens IS required. At least in the manner I was trying to do it.

Steve A.

*I'm still impoverished, nothing changes!


Hi Steve so the camera would of had a pin hole for the lens ...did you try scanning a slide close to it with an adjustable light behind that might work and over come low light levels of a pin hole the other way around as i am trying with the monitor screen needs to be about a mm from the pin hole for focus or to bring the light level up enough to work for me might be the same way around for a camera ?

Thats a great idea reusing a record player a record player , i was thinking some time back if i could speed right it would be a great strong base for a mirror screw idea .

Yes its a problem mounting the vertical arm and or sensor on the rotating turntable you could mount polygon mirror on the turntable and then the vertical arm funny enough might go where the record stylus arm sits with a lens you would have one mighty camera !

You never know these thing unless you try give it a go .

Thats an interesting project .

I know its great to make it and show stuff that works and no one likes to fail ,i think it is equally good and showing steps anyone else going down that road will know where you or i have gone wrong ..more so me Yakes and very less so Steve !

:wink:
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Postby Steve Anderson » Thu Jun 16, 2011 12:52 pm

Initially this was to be a 'live' scene scanner, but with no optics there's no problem with focussing, simply place said photo in front of scene. So given enough light on the photo it should have worked.

But my problem was the photo-sensor arrangement. After reading about projects like Chis Longs' long-range optical communications I was increadulous that I could not get a decent signal when midday sun here on a clear day is something like 10,000 lux!

I did something fundamentally wrong, don't ask me what but I must have. As I mentioned before, I intend to re-visit this one day but my starting point will be the photosensor whatever form it may take.

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Idea for an SSTV camera

Postby kareno » Thu Jun 16, 2011 8:01 pm

Here's an idea I had many years ago for an SSTV camera. It's a rotating lead screw that causes the end of a fibre to scan a raster of sorts (the drawing doesn't mention that the fibre can slide freely through the threaded component on the threaded bar).

I had hoped this could run at NBTV rates but I suspect there would be such violent movements that it would break itself off its mounts! So I never tried it.

Oh yes - I've left out all the microswitches/opto sensors that would be present to stop the thing falling off the end of the thread!
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Re: Idea for an SSTV camera

Postby Harry Dalek » Sat Jun 18, 2011 12:57 am

kareno wrote:Here's an idea I had many years ago for an SSTV camera. It's a rotating lead screw that causes the end of a fibre to scan a raster of sorts (the drawing doesn't mention that the fibre can slide freely through the threaded component on the threaded bar).

I had hoped this could run at NBTV rates but I suspect there would be such violent movements that it would break itself off its mounts! So I never tried it.

Oh yes - I've left out all the microswitches/opto sensors that would be present to stop the thing falling off the end of the thread!



Hi kareno
i like the upload idea but would change a few things being me !...looking at it i like the motor design for the vertical i would gear that for the slow vertical down up movement ..
i would just have a rod where you have the long screw ,so the horizontal arm would just move left right fast on one place in the middle of the arm .
And i think the light transistor could be on the front of the fast horizontal arm .

i think shorting the fast moving arm would be better to stop vibration .

i was nearly going to try the hard drive voice coil for my monitor horizontal i know it would work as it does for 12.5 hz nbtv 16hz may be a touch less so but not to far off my vibrating voice coil tests with the laser i did at 12hz.

Steve thanks for the info on your mechanical camera idea i find it interesting and i like it and also find it interesting when you have a go at the mechanical side of things .Cameras i was always thinking would be easier than monitors for nbtv and sstv but looks like not mmm.







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Postby Harry Dalek » Tue Jun 21, 2011 5:49 pm

Hi had some ideas today and kareno has inspired me to do some drawings.

I was thinking of glow paint test gear ...how do you test if theres enough light to burn an image on the drum or the flat .

doing it simple

So heres a few different ideas to test without having to much in the way of electronics sort of a step i would have done or should try now for light levels.

i like the last as painting a raster over the 35mm film should show if an image stays long enough with the light levels you have .
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Postby Klaas Robers » Wed Jun 22, 2011 8:36 pm

Harry, don't expect too much from the afterglow. I remember from the time that I was experimenting with SSTV (about 1973) using a 7BP7 tube, that the afterglow is so short that you are looking at the last 1 or 2 cm of the picture, while the earlier part was already gone more or less. Only in the dark it was possible to get a kind of overview of the total picture of 8 seconds, however there was a huge difference in contrast between the lowest part, just written, and the upper part, written 7 to 8 seconds ago.

But if the afterglow had been much longer the previous picture would have been still visible through the new one. This happened already, when it was dark enough.

So you should have a still standing screen, where the lines are written while you can watch the coming of the picture. There is no use to scan (move) the screen and hope that you can watch the picture after it has been written when you halt the screen.

On top of that, if you would do so, the next picturelines are already coming in while you hope that you are observing the picture. So you will miss half the amount of pictures.
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Postby Harry Dalek » Thu Jun 23, 2011 12:39 am

Klaas Robers wrote:Harry, don't expect too much from the afterglow. I remember from the time that I was experimenting with SSTV (about 1973) using a 7BP7 tube, that the afterglow is so short that you are looking at the last 1 or 2 cm of the picture, while the earlier part was already gone more or less. Only in the dark it was possible to get a kind of overview of the total picture of 8 seconds, however there was a huge difference in contrast between the lowest part, just written, and the upper part, written 7 to 8 seconds ago.

But if the afterglow had been much longer the previous picture would have been still visible through the new one. This happened already, when it was dark enough.

So you should have a still standing screen, where the lines are written while you can watch the coming of the picture. There is no use to scan (move) the screen and hope that you can watch the picture after it has been written when you halt the screen.

On top of that, if you would do so, the next picturelines are already coming in while you hope that you are observing the picture. So you will miss half the amount of pictures.


HI Klaas

Thanks for your input i don't remember what my sstv p7 crt was but it needed magnetic focusing and was magneticlly deflected ...i recall viewing it in a darkened room so yes they were poor for light levels with the top part fading towards the end of the scan .

With my experiments with uv leds and seeing the blue laser computer controlled laser scans on the glow paint others have done its a bit different to crt phosphors ....only in that the the light levels on the after glow can be improved on where a greater light level directed to the paint
longer it with stay ...trying this on a crt i think you would burn your phosphor screen .

Yep i think the next image might not over write the last depending on the light levels of the last .

i was thinking a blank raster scan before the next image is tried might fix this like the kids toys that wipe the drawing before they draw another picture .

i also found this
Red laser 630nM+ will `switch off` an activated glow pigment which is interesting

One thing i am not sure about is as a crt can give white to black but i think glow paint the high to low light levels are poorer no black ! yes sort of a lot of contrast Oh well work with what it can do i say .

The moving screen idea with the rotating drum lens is the hardest i have tried a bit different ...the rotating mirror and flat screen is best but i didn't have the laser at the time ....using uv leds to get the right light levels for a 8 sec scan it has to be focused a mm to the screen focusing that and directing it to a screen bit large for the light levels used + the distance dropped the levels to much it was dim even in the dark.

I too am thinking the best way is a flat screen now i have the laser thats no real problem ,the lens on the blue laser i have is removable its focus spot looks a bit large so i will have to look into this .

Anyway in the mean time i will try one or two the 35mm flim experiments on the paint see what the image burn is like perhaps wait 8secs place another over and see if theres a problem with the previous image ...

i will post picture results i have a few days off to play around with it again .
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Postby Harry Dalek » Thu Jun 23, 2011 2:19 pm

Today io tried the 35mm film experiment from the top of my drawing from the past posting.

It works i didn't try it in the dark but just in room light .

The image stays for some time but the sharp images fades quick in room light ,i will try it in the dark tonight .

My Blue laser is a bit different to the green one remove the lens on the green you have a torch the blue does not have a lens in the removable part so i put the green lasers on the blue and it gave me a torch in other words to try this.

All i can say is the image is sharp and you can do the same with the negative above the screen and blow up the image but its dimmer.

The experiment is really just to see how long a image would stay viewable
on this stuff some light is lost with the passing the negative...and i am directing all the laser light over a large area..

Also i tried the red laser over the glow paint after its been charged with the blue laser it does cancel the light but my red is only a 1mw so i expect
it would be better with a stronger red laser .

Writing it over with the blue works pretty quick so i am not sure if the red idea has much use for me and you can do this over a large area at once.
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Postby Harry Dalek » Sat Jun 25, 2011 12:58 am

MSSTV steps is a good title for this fickle as ever i am ...i was checking out my junk box and noticed a stepper motor and gears out of a scrapped laser printer i scrapped a few weeks back .

This had me working out a new design which due to now knowing what problems i have had with the other ideas i have come up with a sort of mix ,

Reusing the glow drum this is mounted on one of the gears for the slow vertical rate ...i want it running so part of the drum for a full scan so this one is good for that .

For the horizontal i now going to try the blue laser reflecting off a past scrapped laser printer polygon mirror which i have used before ....gets around this polygon mirror!

Testing yesterday the Blue laser with the green lasers removable lens it gives a fine point of light the focal point something like 15mm or so here or there which i hope to adjust right reflecting to the drum .

In the photos the dot can not be seen but to the eye its very fine what i need to do is cut off a bit more plastic from the housing of the polygon mirrors in so i can get closer to the drum.

Need a fine raster dot and enough after glow for me to progress so i think if i can get the focus right ( which you might find strange using a laser ) but the lasers spot is not fine enough ,gives a rather thick line scan using it with its built in lens.

All the other go's i have had poor after glow apart from the first, this one is truly the other way around to the first swapping the horizontal scan of the drum to the vertical slow scan making life much easier ...and a scan viewable while rotating ..

BTW it will be on its side drum rotating and polygon laser scanning lines right across from the bottom to the top of the drum or really sideways .

So there you go another go another design i can see problems more easy to control with this one.
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Postby Harry Dalek » Sun Jun 26, 2011 5:10 pm

I got my first Blank raster with the laser going yippee ! :D

I took a few close ups of the raster lines on the drum ,this is controlled by the stepper motor and the polygon mirror.

Now the laser lens gave me some problems with the focal point...i had to drop that idea for another ! which works but drops the lasers light a bit ...

The focal point problem was at the focal point the polygon mirror can not rotate the laser hits it ...so thats no good ! :shock:

So i tried something i noticed when i was playing around with the red laser some time back adjusting the laser to the edge of the polygon mirror you drop the spot size and it is adjustable as the mirror is something like 3mm thick.

As you see it gives a rather fine raster line. only problem is you drop light levels a bit but with the laser and seeing these photos in room light i think it does better than a p7 crt.

Now i can move on .

I will upload a AVI or 2 of the thing working more impressive than any photo.
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Postby Harry Dalek » Sun Jun 26, 2011 6:32 pm

Heres the video of my new msstv idea working blank raster ,line rate not correct yet just wanted to show line painting.

Also its not really at full laser strength i have it knocked back a bit while i was adjusting the laser to drum .

Still its pretty good should be able to get the correct line rates with this system..not as fragile as the other go's and its more compact...never knew that scrapped laser printer would come in handy for this .

need to start doing modulation tests now.
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Postby gary » Sun Jun 26, 2011 7:28 pm

Sorry Harry, I must have missed something, what's that slow flashing light over the entire scene?, otherwise it's starting to show some promise.
Perfecting an NBTV system is like trying to slam a revolving door...
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