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 » Mon Mar 28, 2011 11:17 pm

gary wrote:
harry dalek wrote:Not using a laser as the glow paint glows in the green Freq so i would need a green laser ......bit costly for me .


I am not necessarily promoting it's use in this instance but I have just ordered one of these green lasers to see what it's like:

http://www.futurlec.com.au/Laser_Diode.jsp

At $13.55 it's not too expensive...


Hi Gary

Looks like part of your Slow scan television schematic will be made soon
.
Yes thats not a bad price ! alot beter than jaycars !
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Postby gary » Mon Mar 28, 2011 11:23 pm

Yeah, the problem with Jaycar is that they now have no competition at all and so can charge what they like. I am afraid that online ordering is the future which is a pity because, in a lot of instances, you never know for sure what you are getting, but Futurlec have been pretty reliable for me.
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Postby Harry Dalek » Mon Mar 28, 2011 11:30 pm

gary wrote:Yeah, the problem with Jaycar is that they now have no competition at all and so can charge what they like. I am afraid that online ordering is the future which is a pity because, in a lot of instances, you never know for sure what you are getting, but Futurlec have been pretty reliable for me.



Had not heard of them i will google !

I like jaycar only because it reminds me of what Dick Smith and Tandy electronics used to be sad should just call them JV Hi FI .
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Postby gary » Tue Mar 29, 2011 9:14 am

I prefer to be able to go in and "see" the things I want to buy, but paying 2 to 3 times the price of online items tends to dampen that down a bit.

The other problem with Jaycar, at least here in Sydney, is that they seem to have placed all of their suburban outlets in the least accessible places - i.e. busy main roads with little or no local parking - seems insane to me.
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Postby Harry Dalek » Tue Mar 29, 2011 6:44 pm

Hi since we are talking about SSTV i found this valve circuit in my collection ....

On the first page it talks about the reason why you can't use normal tv crt for the project..

I am not sure this stuff works a bit like something transparent but with light if so and you coat your CRT and you have perhaps a P7 CRT for free, if so they were wrong .
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Postby Steve Anderson » Wed Mar 30, 2011 7:19 am

Well, I've only been out of circulation a few days...and how this thread has taken off! Which is good to see. It may well provide other methods of NBTV scanning and display with some cross-fertilization! Here's hoping.

I'm now in the UK and my body-clock is almost adjusted to the local time. So without a workshop at my disposal all practical work has ground to a halt until my return home...a matter of a few months.

But I'll be here just as often...did I hear groans?

Steve A.
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Postby Harry Dalek » Wed Mar 30, 2011 3:45 pm

Steve Anderson wrote:Well, I've only been out of circulation a few days...and how this thread has taken off! Which is good to see. It may well provide other methods of NBTV scanning and display with some cross-fertilization! Here's hoping.

I'm now in the UK and my body-clock is almost adjusted to the local time. So without a workshop at my disposal all practical work has ground to a halt until my return home...a matter of a few months.

But I'll be here just as often...did I hear groans?

Steve A.


Hi steve

I just started to do some electronics to control the vertical on the LED motor arm this should tell me how well i can adjust one line under the next ...its really the only big problem if i can get that right the rest is easy ...i have been itching to start on the control electronics all week it was good to get the soldering iron in hands just before .

On the nbtv side ! i have been thinking about this since the the glow in the dark paint really is how long and how bright the led is on the surface the nbtv would be very much less due to the horizontal sweep nbtv tv standard .

Oh well i am very happy with the MSSTV so far and working out in my head the steps ...


But for a start all i want to see is a tin will 120 lines fadeing away after 8 sec's which i hope to see in the next day if i can control the led arm enough in small enough steps .
Last edited by Harry Dalek on Wed Mar 30, 2011 9:23 pm, edited 1 time in total.
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Postby M3DVQ » Wed Mar 30, 2011 6:13 pm

harry dalek wrote:On the nbtv side ! i have been thinking about this since the the glow in the dark paint really is how long and how bright the led is on the surface the nbtv would be very much less due to the horizontal sweep nbtv tv standard


how about a spark gap? could that create a more intense light (also gives of lots of short wavelength light does it not?)

Then again, I suppose you want to modulate it which would be almost impossible
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Postby Harry Dalek » Wed Mar 30, 2011 8:37 pm

M3DVQ wrote:
harry dalek wrote:On the nbtv side ! i have been thinking about this since the the glow in the dark paint really is how long and how bright the led is on the surface the nbtv would be very much less due to the horizontal sweep nbtv tv standard


how about a spark gap? could that create a more intense light (also gives of lots of short wavelength light does it not?)

Then again, I suppose you want to modulate it which would be almost impossible


No its not a type of light problem at all for the glow paint you don't want to much more .

an idea would be is use 32 leds tiny ones side by side you can guess the rest ! no mirrors just a bit of led switching and focusing .

Harry
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Postby AncientBrit » Thu Mar 31, 2011 5:41 pm

Harry,

If the afterglow of the paint is measured in hours rather than seconds as for a CRT, how are you going to erase an image before you apply another?

If you keep adding new images the net result will surely be an overlay of all previous images leading eventually to uniform illumination.

Regards,

Graham
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Postby gary » Thu Mar 31, 2011 8:04 pm

An erase mechanism? yeehah takes me back to my Tektronix 4014 days...
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Postby Harry Dalek » Thu Mar 31, 2011 8:23 pm

AncientBrit wrote:Harry,

If the afterglow of the paint is measured in hours rather than seconds as for a CRT, how are you going to erase an image before you apply another?

If you keep adding new images the net result will surely be an overlay of all previous images leading eventually to uniform illumination.

Regards,

Graham


Hi Yes it is but if you notice the video and doing a night test the fade its enough to write over just like a p7 or normal crt would do writting over the last image line ...if you see the day time test i did its really dependent on the light levels in the room lighting and the intencity of the light your directing on the glow paint ....So adjust the the led to night day levels,,,


Yes it does glow and i expect you'd see the last image for some time if nothing is rewritten to it ..



The glow paint it not the problem or the lighting to it ....its adjusting one line after the next .

I was hopeing to use the motor on the led arm but sending pulses to it gives to much of a jump gravity doesn't help either...i need gearing for this slow speed and lucky enough the CD or dvd disc drive door seems to adjust on pulses which i want tiny steps for each line ....if its small enough i might go with this other wise off to jaycar electronics and buy a geared motor to attach to the Led Arm.

As i said all this stuff is nothing new its just a fax machine with a rotating
phosphor nothing apart from the phosphor idea is new so i know it all works apart from my construction skills ! :roll:
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Postby AncientBrit » Thu Mar 31, 2011 10:59 pm

Thanks Harry, so adjust room lighting for apparent afterglow!

Tell us more Gary....

Regards,

Graham
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Postby gary » Thu Mar 31, 2011 11:20 pm

AncientBrit wrote:Tell us more Gary....
Graham


About the 4014? That's what we had to do CAD/CAM on in the middle to late 70s - it was a vector graphics workstation - the CRT was a "Direct View Bistable Storage Tube" which stored whatever was written to it until "flashed" (very similar to an etch-o-sketch) - you would draw on it and if you wanted to move or delete anything you would have to erase the whole screen by hitting the "erase" button (what else? edit: well actually it was the "reset page" button ;-)) which "flashed" the tube a bright green - the whole drawing was then redrawn - the redrawing was so slow you would hold off "flashing" until the screen was so messy with edits you couldn't read it any more - you then "flashed" and went for a coffee - what fun!

They weren't as bad as they sound - the vectors were very sharp and were closer to a real drawing than the vector screens which at that stage were still to expensive for reasonable resolution.

The workstations had two thumb wheels at 90 degrees that were used to position the crosshairs - I have always felt that for CAD these are better than a mouse.

aaah the good old days...


edit: resolution 1024 × 780 pixels. - not bad for early '70s
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Postby Harry Dalek » Fri Apr 01, 2011 1:13 am

AncientBrit wrote:Thanks Harry, so adjust room lighting for apparent afterglow!

Tell us more Gary....

Regards,

Graham


Hi graham


Theres a differance viewing in the dark to a room in day light the after glow fades more or less to how much light is in the room .

The day light test shows i can write over lines as i did it in the video .

Adjust your led to room light more in the day less at night or room lighting yes just like for a p7 sstv

I have not got to the sstv circuit yet but i am hopeful ..for me i would not care less if it just gave one image in ages point is trying fun .

I have been working on the vertical speed control trying to do it on the cheap! i have gearing to test nice and slow now sort of bits from dvd drives and beta vcr see what it does when i hook it up tomorrow .
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