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Old 23rd Oct 2019, 10:53 am   #1
dalekmoore2007
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Default SSTV Mechanical video recorder Attempt

I am working on phonovision but got to start some where ...i did start by seeing if i could record any thing no matter how bad but got to the point where voice music was ok then i had plans to widen my bandwidth with SSTV which to me is a step i always wanted to do record it on a record ...early 33rpm recordings were very very poor funny enough but in sync i found you really need at least 45 and much better 78 Rpm for this system
Looking into Albert's great work on wax drum NBTV and Jeremy Jago in 2006 NBTV has inspired me...and of cause the Great John logie baird .
I didn't want to use a working turntable wanted to make it from scratch so lots of trial and error and design changes ...This did make it very difficult as i am finding now on syncing the lathe to a standard 78 rpm player ~!
This is what you are seeing in the youtube video below the lathe is a bit out speed wise so is the syncing then as shown .
I think due to the problem with a dc geared motor syncing it would be easier to just work on a play back head arm for the lathe and i can adjust things much easier from the same machine without making it standard for now but that my follow in time .
I also had a few go's at designing the lathe cutting or embossing head ended up here so far using a dvd stepper motor wired soldered to a a gem play head of some sort shown below ...
https://www.youtube.com/watch?v=svpDroXEqIQ
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Old 29th Oct 2019, 12:39 am   #2
dominicbeesley
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Default Re: SSTV Mechanical video recorder Attempt

Brilliant! I wouldn't have thought that much was possible.
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Old 30th Oct 2019, 7:57 am   #3
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Default Re: SSTV Mechanical video recorder Attempt

Didn't RCA have a go at this and ended up going bankrupt? They had all sorts of issues and released a player at the same time as BHS came out, I think. Admire your tenacity, clever stuff.

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Old 30th Oct 2019, 11:00 am   #4
dalekmoore2007
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Default Re: SSTV Mechanical video recorder Attempt

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Originally Posted by dominicbeesley View Post
Brilliant! I wouldn't have thought that much was possible.
Hi Dom long time no see : )

Well the big problem is NBTV Baird dropped the bandwidth with 5 frames a sec 30 line. No syncing 78 RPM

Well i am doing at the moment 78 RPM one frame per 8ec 120 line and i have no syncing either all manual at the moment ...i will post some pic's

I did end up making the play back arm with ceramic cartridge so i am play back the recordings on my lathe and adjust the speed as with no syncing i am am the syncer !

As you see the results are rough but playing back video from scratches on a cd this is pleasing, and gives me hope to go on i want to try other SSTV modes fax so on but i need to sync which is my next step. I went with SSTV as i know it is easier and it gives me a test bed to see what works what doesn't there have been many redesigns !
I hope to do a type of phonovision in time i can see next year being a lot of head scratching ..have to say this is the hardest project i have ever tried.
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Old 30th Oct 2019, 11:41 am   #5
dalekmoore2007
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Default Re: SSTV Mechanical video recorder Attempt

Quote:
Originally Posted by Diabolical Artificer View Post
Didn't RCA have a go at this and ended up going bankrupt? They had all sorts of issues and released a player at the same time as BHS came out, I think. Admire your tenacity, clever stuff.
High Andy well it is a dreadful way to record and play back video so i can understand that even Baird gave up and never gave it a go again he was never happy with the results !

Most people make record lathes from old players results good or bad depending on your macgyvering skills video sort of harder due to the bandwidth needed to record this and the syncing/
below my player and recorder same device i just change the play or record arm cartridge the old cd or dvd motor you see on the side i just use for the up and down movement and the magnet it holds the arms they just snap on and off so easy to change for record or play back .i will post up if i get to another step pity i can't upload video here .
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Old 1st Nov 2019, 11:29 pm   #6
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Default Re: SSTV Mechanical video recorder Attempt

All you need there is a time-base corrector. You'll need some storage, perhaps a bucket-brigade delay-line. Obviously you will want to use real buckets...
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Old 2nd Nov 2019, 2:42 am   #7
dalekmoore2007
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Default Re: SSTV Mechanical video recorder Attempt

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Originally Posted by rambo1152 View Post
All you need there is a time-base corrector. You'll need some storage, perhaps a bucket-brigade delay-line. Obviously you will want to use real buckets...
The geared motor needs some sort of syncing ..my plan today was build a sstv demodulator to get the 15 hz line sync which is varying frequency due to motor speed ...feed this into a 4046 PLL with also a clock at 15 hz for some motor control with feed back .
Problem also with a record is speed changes playing from the edge to the center...there's a lot of mechanical things going on apart from the electronic side..
I will look into the delay line idea something i have not thought of .
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Old 2nd Nov 2019, 7:57 am   #8
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Default Re: SSTV Mechanical video recorder Attempt

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Originally Posted by dalekmoore2007 View Post
I will look into the delay line idea something i have not thought of .
My suggestion was at best 10% serious
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Old 2nd Nov 2019, 2:07 pm   #9
dominicbeesley
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Default Re: SSTV Mechanical video recorder Attempt

The pll board is probably a good idea...but first centre the disc and you could try adding a load of weight to get a good flywheel effect?

D
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Old 2nd Nov 2019, 10:22 pm   #10
dalekmoore2007
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Default Re: SSTV Mechanical video recorder Attempt

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Originally Posted by dominicbeesley View Post
The pll board is probably a good idea...but first centre the disc and you could try adding a load of weight to get a good flywheel effect?

D
The platter i am using is a thick bit of steel i think from an old vcr motor which could of been used for that ,just happened to be and fit what i needed here ...i will keep that on mind once i try the syncing adding more weight if it helps.
The motor is small from a video camera zoom lens 80s perhaps its geared which i needed for the lathe part to keep the platter to a constant speed when embossing the the cd dvds with a lot of friction ( viewing the speed via a strobe disc and laser to it and a photo transistor viewing on a frequency scope ) ...trouble might be syncing 15 hz is pretty slow we have only really tried it at 400 hz 750rpm for nbtv with nothing touching the disc ..here 78rpm with a bit of fiction from the play back arm ...
I think the idea Dom of using the recording sync pulses would be the way to go as you think also.
I need some sort of feed back to keep the sync pulses at the correct frequency as the motor for the platter spins the disc .
I have a 15hz clock and once i finish the SSTV demodulator i can add the sync circuit for the line frequency from the record recording feed both to a 4046 PLL for motor control ..just makes it more complex but a good test bed to see this is possible at low speeds...must be possible old facsimile machines were even slower they manage to sync them one way or another.
At the moment in the photos i posted up i am just adjusting platter speed now and then on play back trying to match line after line that's why the image's are wavy the line sync pulse's going in and out of sync frequency ...
Working more on the demodulator today..
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