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 » Fri Apr 01, 2011 12:54 pm

Hi i finished the gearing to the vertical arm runs very slow now on pulsed voltage which i hope will now give me line under line ...it looks clock work when running i can adjust the speed up down to what ever but if i am working it out right i need it to do 15 lines a second for 8 seconds 120 lines.

I am not expert in gearing but it seems to run nice i could do a 8 second drop by the looks of it or less .

I'll do a test tonight with the LED

i was worried about the reset problem after i made it but it does run fast back to reset if i apply just a few normal un plused volts to the motor thats driving it .

Oh i used an older CD ROM drive for this i used the laser arm lens and the cd eject motor gears and a few bits out of a beta vcr and a rubber band !!
Attachments
IMG_0001.JPG
THe gearing
IMG_0001.JPG (73.84 KiB) Viewed 14723 times
IMG_0003.JPG
IMG_0003.JPG (79.6 KiB) Viewed 14723 times
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Postby AncientBrit » Fri Apr 01, 2011 5:36 pm

>Gary,
Thanks for the blast from the past.
Things are a bit easier now though aren't they?

>Harry,
I'm impressed with your mechanical skills. How do you find the time though?

Graham
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Postby gary » Fri Apr 01, 2011 5:46 pm

AncientBrit wrote:>
Things are a bit easier now though aren't they?
Graham


Faster anyway...

(still wish I had the thumbwheels ;-))
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Fri Apr 01, 2011 11:14 pm

AncientBrit wrote:>Gary,
Thanks for the blast from the past.
Things are a bit easier now though aren't they?

>Harry,
I'm impressed with your mechanical skills. How do you find the time though?

Graham



Graham Yes time is the problem lucky for me some times i can have a thursday or friday off if i get my work done .
Then between looking after a 1 and 3 year old i can just manage to get to the soldering iron between nappy changes.
I am sure every one is in the same boat love to do the hobby but life gets in the way.

Doing Dom's circuit and this and plan to do the sstv electronics which i was going to do anyway.

Arrrr nothing like spare parts and a hot glue gun! 8)

Time got in the way tonight and beat me again i had a bit of trouble with the older laser lens when i was remounting the led had to drill the hole wider so it could fit you'd think the older one would be easier ...then you have to refocus the thing.

OH gary yes Jaycar have crap parking and lucky fort me there is one close for a change .
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Postby Harry Dalek » Tue Apr 05, 2011 12:50 am

Hi

Took some photos the other day of how i was remounting some stuff on the project .

Thats how i do thats how i mount the drum and the led on the thing.

This is also what it looks like at the moment ,i have the arm controled in a way relay control to reverse the arm motor ..the electronics is that and motor control speed .

So just working things out step by step .

When i do a run test i will video tried the other night but my camera which is good on low light is playing up my luck.
Attachments
IMG_0005.JPG
This is how i connect the drum to the motor ..hole in connect to the hd via screws the lid and pops on : )
IMG_0005.JPG (86.86 KiB) Viewed 14698 times
IMG_0006.JPG
l make the lid hole a bit bigger so i can just adjust it for the middle never ever get it right drilling this way move a bit and tighten screws
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IMG_0007.JPG
working out the new laser diode lens laser removed for the LED
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IMG_0008.JPG
I ended up using the orignal len with an end to as pug to mount the led in makes it adjustable for focus
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IMG_0010.JPG
working out focus distance didn't end up using the foil over the plug wasn't needed in the end
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IMG_0012.JPG
lens led mounted on the vertical arm
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IMG_8554.JPG
what it looks like today sorry about the focus
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IMG_8556.JPG
This ones better and i have a spare drum to test as well.
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IMG_8551.JPG
Heres the viewing space distance i will get with the dvd drive arm
IMG_8551.JPG (48.15 KiB) Viewed 14696 times
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Postby gary » Thu Apr 07, 2011 1:40 pm

Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Thu Apr 07, 2011 9:26 pm

gary wrote:similar principle:

http://drebsdorf.net/default.aspx?id=2#14


Hi Gary

Yes sort of the same idea useing phosphorescents and light to draw but doing it on the flat . always interesting how you can do the same sort of idea differently.

I am just about finishing of the control arm its on on sort of automatic control to reset its self i can put it on manual if reset is to slow .

need to speed it up a bit to 8sec's

Ok the green led is the bistable 555 timer Multivibrator this switches a tiny relay which controls a bigger 12v relay which reverses voltage either way to the led arm motor , pulsed voltage from the yellow leds 555 timer is used for this ...i have reed switches above and below the led arm which sets and resets the bistable Multivibrator.. so the whole thing controls its self .

Next step is to get the drum to control the timer which contols the led arm motor , could get the sync later to control either but thinking the drum could control the arm now,but we will see ..
Attachments
MVI_8558.avi
MY led arm control and reset
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Postby Harry Dalek » Fri Apr 08, 2011 3:02 pm

Hi all

i was working on the arm again think i am about a second out for speed but thats just an adjustment now.

Heres a video of it working better than the last front back views...

Just a bit of work to do on the drum motor and and start on the slow scan electronics .
Attachments
MVI_8557.avi
This is a better video of the arm working front back
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IMG_8551.JPG
IMG_8551.JPG (91.74 KiB) Viewed 14655 times
IMG_8558.JPG
IMG_8558.JPG (97.63 KiB) Viewed 14655 times
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Postby gary » Fri Apr 08, 2011 7:38 pm

Harry, you have the makings of a great Z axis for your CNC machine there. ;-)
Perfecting an NBTV system is like trying to slam a revolving door...
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Postby Harry Dalek » Fri Apr 08, 2011 10:51 pm

gary wrote:Harry, you have the makings of a great Z axis for your CNC machine there. ;-)


I wish i am a long way off making something like that .

My thinking so far since i have added magnetic field sensors to the drum
2 for testing one any ordinary reed switch and the other out of a beta vcr which seems to change resistance to a magnetic field so i am trying that out either side of the drum {think it was used for tape stop}...could go with lots of ways with light but have these handy..so going magnetic (also lazy to drill a hole in the HD platter!...was going to try one or 2 old relay coils with the magnet on the drum as now but trying the above first .

Well this on off or resistance change as the drum rotates i hope to trigger a monostable 555 timer the red led on my board i will use this monostable to speed up and slow down the Led arm( depending on the drum speed}, since i am using one pulse per drum revolution 15 revolutions of the drum per second 15hz should give me in movement down on the led arm 15 lines space i hope ! so after 8 seconds 8 times 15 lines should give 120 lines of good old classic SSTV.

So i am off to hoook up the monostable and see what happens .

I think i could be in trouble in that it may work in the speed way but may expect a longer drum i might have overlapping lines due to raster line thickness..one of those things see what it does when it does it :shock:

I have orded UV leds as it might work better since every one playing around with glow paint seems to be using these my white led might be emitting part of this freq along with every other colour.
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Postby Harry Dalek » Sat Apr 09, 2011 5:02 pm

Well sort of at Stage 3

I changed a few things to make the thing work...Now the red Led 555 timer is being controled by the drums reed switch this timers output pulse voltage controls the arm motor speed ...so if the drums going 15 or 16hz
this arm should be dropping 7 or 8 seconds per scan ...looks like its works and my freq meter says its close .
I also have now the{ yellow led } the motor speed contoller 555 timer the thing works in a loop .
later on i will be using the vertical sync from the sstv circuit sync sep to trip a relay to start a scan ...the horizontal will be fed to the drum motor 555 timer drum motor speed controller.

Heres a video of the thing working so far i have misplaced my orignal high bright led using a replacement not as good but show it works i will do a night test to night as film should look a lot better than this in the day light . and using a better camera tonight its better at low light levels.

I expect the uv leds coming should improve things as well.

Now i can start on the sstv circuit .i will be mixing and matching stuff i have made over the years ...so it will be more than likly and 555 timer and 741 omp amp mechanical tv .
Attachments
SANY0017.avi
Heres it working with drum and led in the day light..
(3.45 MiB) Downloaded 311 times
2SANY0019.avi
close up of the fade its low in this day light and smaller led
(5.86 MiB) Downloaded 317 times
Last edited by Harry Dalek on Sun Apr 10, 2011 12:22 am, edited 1 time in total.
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Postby Harry Dalek » Sat Apr 09, 2011 9:41 pm

Hi just did the night tests will post shortly i am very impressed even with this lowwer Led its spot on about the same as i recall a p7 crt would do.

The camera gives half as good as i can see with the eye which i know you know about trying to take nbtv photos.

Just a raster but the first glow tin one .
Attachments
IMG_0009.JPG
first photo
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IMG_0029.JPG
IMG_0029.JPG (115.67 KiB) Viewed 14613 times
MVI_0030.avi
night with room light on
(2.56 MiB) Downloaded 339 times
MVI_0011.avi
lights off
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Postby Harry Dalek » Mon Apr 11, 2011 11:45 pm

Just to let you know where i am up to i was checking what circuits to start up with making the sstv electronics ,i was going to tack some together that i have made before but looking at my sstv companion booket it has a nice one i am going to pinch for this project ..just so happens i don't need to scan it as the books on line he's the PDF its a bit different to my book looks like an update but the circuit i am using well apart from the digital part dont want that is on page 37.

Just want to drive that LED and use the sync sep that will do just nice .

I have been soldering away only up to the second ic will take me a few more days to finish this off .
Attachments
sstv.pdf
interested in sstv this is a must .
(3.43 MiB) Downloaded 436 times
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Postby Harry Dalek » Tue Apr 19, 2011 3:30 pm

Well i am at the testing stage .

The uv high brightness led i tested last night did the trick its very good even drawing lines at very low light levels .

I made the sstv circuit the led light modulating part of it seems to work but need to stick a transistor on the circuit to drive it .

also have made a pll to lock onto the horizontal .

i have realised a flaw in the system idea ...well i think !

Since the drums rotating i could only view after i stop as with a paper rotating around a drum you need to stop to view the fax ...mmm i am thinking perhaps a shutter to view it as its working (mechanical idea } or a strobe light the electronic idea i rather like since the drums glow paint is uv Sensitive if i use a light in perhaps say red i'd have the strobe effect without it effecting the uv light Sensitive paints raster being drawn ?

So i am going to do some experiments like wrap a photo around the drum
and use a strobe to stop it as viewing the photo on a drum not rotating then i will just put a uv light dot on the drum rotate it and see if that can be viewed and stopped as well...

So if the above works then the raster should look like its being drawn like on a something not moving ...thinking of a bistable switch and ic relay to switch on the led to draw raster lines on say half or quarter of the tin to give a crt effect to it .

So if you were wondering i am still working onit !
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Strobe_2.gif
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Postby Harry Dalek » Sun Apr 24, 2011 12:59 am

Hi had been rethinking the design last few days i tested the stroboscope idea
on the rotating drum i didn't think the image would be sharp enough bit of blur and started to get a bit complicated controling 3 motors ,i think its always best to try to do something easiest way.

The rotating drum would be better for an nbtv idea with a rotating polygon.

Oh well live and learn and try not to give up !

So i have redesigned the projection part.

Instead of a rotating glow paint drum i now have a rotating double sided mirror projecting the uv led to a glass painted in the glow paint .. doing this i also had to redesign the lens part which was a bit of a pain trying to work out the focus point using two lenes using what i had for the size needed..reused the dvd laser lens and a camcorder eye piece lens.

Of cause using a blue laser would make life easier and i have one coming to see but just wanted to test this for now.

One interesting effect i noticed with the glow paint if it painted on a mirror its more effective as its being reflected back i had some paint on my dvd platter which has a mirror finish.
Attachments
IMG_0120.JPG
heres the redesign
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IMG_0121.JPG
look at the double side mirror projection lens
IMG_0121.JPG (78.47 KiB) Viewed 14546 times
IMG_0122.JPG
using the mirror means the focus is not as close and needs 2 lenes
IMG_0122.JPG (96.36 KiB) Viewed 14546 times
IMG_0123.JPG
the first lens is half way along that white arm the uv led is butted up to that
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IMG_0124.JPG
mirror rotation test
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IMG_0127.JPG
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IMG_0128.JPG
IMG_0128.JPG (66.96 KiB) Viewed 14546 times
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