My Christmas present to myself - MUTR mechanical televisor

[Ian - G4JQT]

My Televisor arrived today, so I expect those who ordered just before/after Christmas will have them about now.

There was quite a lot of interest on the forum about this kit so I’ve put down some notes below…

Clear instructions make it very easy to put together in about 30 minutes. No soldering is required as the board is pre-assembled. A slip with the instructions in part states:

“The creators of this miniature Televisor have paid the Narrow Bandwidth Television Association the compliment of adopting its scanning and synchronisation standards and incorporating published motor control circuitry.”

The single LED is red/orange and gives an identifiable picture that is about ¾ inch diagonal, best viewed from about a foot to 18 inches in near complete darkness.

When completed, the unit stands about 7½ inches tall, 10 inches long and 2½ inches deep.

As soon as the unit is switched on with no input connected, it displays a simple test card which is internally generated.

The CD it comes with has nine tracks with silent stills of people I mostly don’t/can’t recognise. Two stills near the end include their voices which aids recognition.

The last track is moving with voice (a well-known speech, but I won’t spoil it!) which is, considering the technology, quite recognisable.

Total length of tracks only six minutes.

The Televisor has no loudspeaker, but has a standard 3.5mm stereo headphone jack.

A pity the CD has only one moving track. The original actors were heavily made up so their features were clearer, so conventional television recordings will probably not be very clear without various enhancements - if that is possible. But I expect the NBTVA can supply compatible recordings as it looks to have been designed in close association with them.

But considering that the stills and short movie on the CD were probably not enhanced in any way, and considering the technology used, the picture is acceptable and almost certainly no worse than was available for the original Baird Televisor viewers.

The only minor addition I would have included in the kit is a couple of plastic spacers to more easily hold the front and back plates the correct distance apart.

At http://www.nbtv.wyenet.co.uk/kit.htm it is suggested that an extra bright 'white' LED and use drawing office tracing paper as a diffuser rather than the one supplied would “improve the picture quality enormously”.

I think the price is very fair when one considers the time taken to design the kit and materials used in it.

Ian

[DoctorWho]

Mine came yesterday, and a very attractive set too! Easy to assemble. I did personally find that the televisor does not sync very well to the recordings on the accompanying CD, I played them back on the PC using the NBTV software and they are pretty poor with off locks and the like. I then used a variety of my own footage to convert to 32 lines, this included original Alexandra Palace continuity announcements with Sylvia Peters, The Doctor Who opening titles and so on, all in all I converted about an hour or so of footage.

I have found that when played via the computer it is very good, the picture is pretty steady and recognisable, however when played on a portable CD player the picture does not lock but impersonates a CRT set which will not allow you to secure the line hold, with out the sync seperator working (the built-in test card is perfactly clear and stable). Any ideas what may be causing this? A poor quality portable CD player perhaps? I am using the Line Out socket.

All in all a very nice addition to the collection. A friend came in and saw it and promptly asked me if it was the back panel to one of the radios or TV sets in the house, that amused me greatly, as, obviously, no one would realise that it is a televisor unless they are involved in the vintage technology circles.

Peter.

[ppppenguin]

Originally Posted by DoctorWho

I have found that when played via the computer it is very good, the picture is pretty steady and recognisable, however when played on a portable CD player the picture does not lock but impersonates a CRT set which will not allow you to secure the line hold, with out the sync seperator working (the built-in test card is perfactly clear and stable). Any ideas what may be causing this? A poor quality portable CD player perhaps? I am using the Line Out socket.

This is only a guess but I wonder if it could be poor low frequency response. Can you view the audio (video!) waveform on a 'scope and compare the PC output to the CD player output. Also the video waveform has a DC component which may well be handled differently by the PC and CD player. Look for "tilt" effects.

[DoctorWho]

Paul - Well I would be very happy to do that, but they come out of the conversion programme as WAV files and some are as large as 56MB (London to Brighton in 4 Minutes for example), and as I am still on dial-up it's not going to be possible for me to upload them, however I would be happy to send a copy of everything that I have converted to 32 lines to another forum member if they are able to make them available for other buyers, this will, at least, allow people to watch a bit more of a variety of footage. I also felt that some early AP footage was a nice touch, I just want to add a few more items, such as Helen McKay's "Here's Looking At You".

Jeffrey - Thanks for the advice, you may well be right, it is a very cheap little portable Cd player that I bought on eBay specifically for this purpose, I think I may well go and look for a better quality one.

A general thought, I do not own an iPod/MP3 player, but I wonder how such a unit would perform as a signal source for a Televisor? I invisaged seperating the two output channels, sending the video signal to the Televisor and the audio signal on to a speaker/audio amp (maybe even a valve radio Gramophone socket). Does anyone here with more experience of these items know if one would be suitable for this purpose?

All the best,

Peter.

[Panrock]

Originally Posted by DoctorWho

A general thought, I do not own an iPod/MP3 player, but I wonder how such a unit would perform as a signal source for a Televisor? I invisaged seperating the two output channels, sending the video signal to the Televisor and the audio signal on to a speaker/audio amp (maybe even a valve radio Gramophone socket). Does anyone here with more experience of these items know if one would be suitable for this purpose?

I remember once asking this very question of Grant Dixon, NBTVA Patron, (now deceased). He seemed certain that this was a bad idea; the compression would maul the phase response quite badly. This might be acceptable with audio but would be no good for video.

Steve

[Panrock]

Well I got mine going this afternoon at last...

The supplied CD wouldn't play at all on my mini player (though it did play correctly in my ghetto blaster - unfortunately no 'line out' there to use though...). However the NBTV club CD does play correctly in my mini player and it is this I used for the viewing tests.

The picture is tiny though excellent, and the little nipkow disc of astonishingly good quality. I wonder how it was made. The video circuitry performs well and displays all the test patterns on the NBTVA CD correctly.

I had some problems with the line phasing of the disc, meaning all too often the picture was bisected by a black bar. It was possible to adjust this out using the disc speed control, but once set this way the sync was fragile and easily lost. So I removed the circular striated sync label from the back of the Nipkow disc (no easy matter!) and rotated it by half a line. Now all is well.

I think this kit makes an excellent 'first televisor' and is excellent value for the money, especially bearing in mind the small scale of production. It's an elegantly engineered product, and they've gone to a lot of trouble to include clear instructions and also some historical background.

I attach a picture of this little beauty standing next to its big brother...

Steve

[Panrock]

Focus? The picture definition on this unit is first class - it sailed through all the NBTVA CD's tests. But I did find I needed my glasses to see it!

When examining the tiny picture through a hand-held magnifying glass, the stippled surface of the diffusing screen could sometimes be seen and tended to break up fine detail on the picture - a different material would help here.

Steve

[Panrock]

Well, it's decided to start working again - I took it apart, inspected it and shook it a bit and that seemed to do the trick.

Here's an attempt at a photo. It looks much better to the eye of course but the size on your screen approximates to the actual viewing size.

I think this televisor has great promise. The difficult things: the disc quality, the video and sync circuitry, are all first class. Where it could be improved is at the display end... a different, flatter-surfaced diffusing screen and a small mosaic of white LEDs there would help perhaps.

http://www.copycoder.com/bvts_images/nbtvdisp.jpg

[jim_beacon]

If you get a loss of synch, try operating in a darkened room - the synch pick-up is very sensitive to mains lighting, and this will cause a synch loss, or split picture. Low energy lights seem to be quite bad.

Jim.

[Dave Moll]

Thanks for the tips about improving the synch. I'll give them a try and report back, including enclosing the unit to shield it from lights - though the best results I have had so far were with it stood in front of the computer screen while connected to the soundcard of the desktop computer. I had previously thought of asking about the distance between the synch markers and the sensor, but then forgot about it - I'll aim for as close as possible without touching.

Having watched the CD using NBTVViewer, I have managed to identify most of the faces. Those I don't are more that I simply don't know the face (or in one case know the face but can't remember the name) rather than the face being unrecognisable - though some are reproduced better than others.

[Ian - G4JQT]

Mine worked first time with the CD in a little Sony Discman, and continued the next day ok too in ambient light. But when I tried to demonstrate it, it just wouldn't lock. Now I can only get it to lock reliably on the internal test card.

I've moved the disk both in and out a little, but hasn't made much difference, even in darkness. I then noticed the stripes had smeared very slightly where the sensor had brushed against it and cleaned it with a soft rubber expecting that to help. It hasn't.

Perhaps there's a dry joint on the board (unlikely as it looks well soldered), or it's very fussy about battery voltage...

[Dave Moll]

As a taster, here are the stills from the first track of the CD:
(courtesy of Gary Millard's NBTVViewer)