Scanning disk television

[yagosaga]

Before some weeks I got a scanning disk from Peter Yanczer. This weekend I have assembled a very simple scanning disk televisor with the first results, see
http://bs.cyty.com/menschen/e-etzold...anningdisc.htm
Is somebody here who experimented with mechanical television? The televisor now is without motor synchronisation. Two MPEG videos demonstrate the effects.
I can install an automatic synchronisation or a manual remote control for the motor similar to that of early scanning disk tvs. What will be a better way?

[tubesrule]

Congratulations on getting your first images on your set!

It is my understanding that all but a few original mechanical sets used some form of frame synchronization. This was usually in the form of a synchronous AC motor that would be on the same power grid as the transmitter, or a small synchronous motor (typically called a phonic coil) that brought the main AC/DC motor spinning the disk into sync. The only set I am aware of that had no synchronization mechanism was the GE Octagon.
You could use the phonic coil method to sync your disk, and this would work very well. I also believe the NBTV web site has a schematic in which an opto-interrupter is placed around a reference hole in the disk, and used to drive a feedback loop to control the DC motor. This method also works very well.

Darryl

[old_tv_nut]

Congratulations! I see that you are using the same type of disc that I bought from Peter Y. It has the synchronization holes (which show as a bright vertical line to the left of your image), and it is relatively easy to build the sync circuit and infrared sensing fork that Peter suggests. Aso, an alternative circuit can be found on my web site, www.bretl.com. I have also seen phonic wheels that work well. Which you use is up to you. Since I am more handy electronically than mechanically, I would choose the sync using the holes and optical sensor.

[yagosaga]

Thank you very much. On the NBTV web site I have found some schematics for synchronizing the disk, using the sync circuit and infrared sensing fork:
http://www.nbtv.wyenet.co.uk/beginners.htm
All parts for this I have, and I will make it in the next days. The disk is fantastic, the lines are perfectly equal. I think this is the best way for now. For synchronising the disk with the correct phase, it is suggested to close one hole of the synchronization holes.
The technology of a phonic wheel I didn't understood, I have to learn it.

[yagosaga]

Originally Posted by old_tv_nut

Congratulations! I see that you are using the same type of disc that I bought from Peter Y. It has the synchronization holes (which show as a bright vertical line to the left of your image), and it is relatively easy to build the sync circuit and infrared sensing fork that Peter suggests.

My NBTV monitor is now working. I have taken the schematics of Peter Smith, but it was necessary to change some details because I couldn't get all the parts here.
http://bs.cyty.com/menschen/e-etzold...BTVmonitor.GIF
Line sync is working very well, but frame sync does not work. I had installed a switch for the frame sync with which I interupt the sync pulse. A lot of pictures and the schematics you will find on my web page (see my first posting). I know that the problem with the frame ync depends on the sync separation. There is noise and some overdriving in the signal.
The monitor now has an "open housing", so everybody can see how it works. In the front side I will install a glas window.
For future work I wish to install a color unit. Do you have any ideas how I can record a RGB color signal together with the video signal in one audio channel on CD?
If somebody wants to get some NBTV videos, please pm me. I send it as zipped WAV files.

[old_tv_nut]

Great results! I like your home-made video file. I tried making some myself, but had some interference between the scanning frequency and the audio sampling frequency.

[andy]

...

[yagosaga]

Originally Posted by andy

Someone needs to make a color scanning disk TV using tricolor LEDs.

I want to add a color circuit, but usually no tricolor LEDs but a number of LEDs of different colors are used. Here is a full-color, LED display calculator:

http://www.hawestv.com/amplifiers/mt.../2or3color.htm

[Eric H]

Originally Posted by andy

Someone needs to make a color scanning disk TV using tricolor LEDs.

And how about High Definition? Drill about 1000 holes in the disk and away you go!
Seriously, could that work?

[Jonathan]

yagosaga,

I must say, this stuff is pretty damn cool, and good work. I'm so amazed by this. I'd definately start such a project but i have lots of bills, two TVs in need of restoration, and a radio in need of restoration. :P