Help with homebrew televisor needed

[Radio_Dave]

Hi,

With all the recent talk about 32 line mechanical televisions I've decided to try and make one

I've found a Peter Smith based circuit on this site http://bs.cyty.com/menschen/e-etzold...anningdisc.htm which seem easy enough (even for me) to follow.

I'll probably have more questions as the build gets going, but just for now can I have some thoughts about making the Nipkow disc? I've found information about how to draw it, but I'm having trouble finding out about diameter, weight and suitable materials I also found in an old 1928 article that suggests the holes should be square, is it worth going to all that trouble?

Another question is about the brightness of the LED's. I've found some orange ones with a brightness of 4000mcd. Would the suggested number of six be bright enough?

Many Thanks
David

[Radio_Dave]

Things are going remarkable well, apart from the Nipkow disc. Several attempts to make one has failed miserably so I have decided to do the sensible thing and buy one from the NBTVA.

I'm a bit confused as to why their disc has a 1.5 turn spiral. I thought there was only supposed to be one hole in the frame at any one time. Wouldn't a 1.5 turn spiral show two in a frame?

Thanks
David

[yagosaga]

Hi David,

the cited web page belongs to me. The making of a Nipkow disk is very difficult. I have bought the Nipkow disk from Peter Yanczer. His Nipkow disks are laser cut and operate very well. For more information see

http://www.televisionexperimenters.com/stuff.html

As an alternative you can order the disk from the NBTV web site.

But before ordering a disk, please check the thread

https://www.vintage-radio.net/forum/...ad.php?t=13264

Kind regards
Eckhard

[Radio_Dave]

Hi Eckhard,

Sorry, I didn't know it was your website...but at least I can now thank you now!

Originally Posted by yagosaga

But before ordering a disk, please check the thread

https://www.vintage-radio.net/forum/...ad.php?t=13264

Yes, it was this thread that got me interested in mechanical television . However, I fancied a challenge so I've decided to have a go at making one.

I've noticed the Peter Yanczer disc before, but it seems a bit expensive, certainly alot more expensive than the NBTV version.

... I still don't get why the NBTVA's version has a 1.5 turn spiral, I wonder if it's to do with aspect ratio .

Thanks
David

[yagosaga]

Hi David,

Originally Posted by Radio_Dave

... I still don't get why the NBTVA's version has a 1.5 turn spiral, I wonder if it's to do with aspect ratio .

Here is a citation from the NBTVA web site:

The club disc has a spiral of 48 holes over 1.5 revolutions. The camera masks the inner 16, the monitor the outer 16 holes. In this way the camera and monitor share the same disc.

and the remaining 32 holes are used for the NBTV standard.

Source:

http://www.nbtv.wyenet.co.uk/cam-mon.htm

Kind regards
Eckhard

[Radio_Dave]

I've just got one more part of the televisor to make, the LED array, but I've got confused .

Please look half way down this page at the 'The LED light source' section http://www.nbtv.wyenet.co.uk/beginners.htm

I don't understand the choice of resistors in either of their examples. I'm using the first design but if the supply voltage is 12V and each of the LED's are 2V 20mA then I would expect the resistors to be 330R not 22R?

However, this is such a common and popular design, I've got a feeling that I've missed something

Thanks
David

[Merlin]

In the text it says the LEDs are 50mA rated, and that additional voltage is dropped across a driver transistor.

[Radio_Dave]

It's now finished and should work but all I can get is a negative image .

What on earth have I done wrong?

Thanks
David

[ppppenguin]

Sounds like the audio is inverted somewhere. Won't make any difference to sound reproduction unless you are one of those golden eared folks who claim to be able to detect absolute polarity but will certainly make video negative.

Either use a different CD player or an inverting amplifier stage between it and the televiser.

[Dave Moll]

Apologies if I'm missing something here, but could it be as simple as the leads being the wrong way round?

[Radio_Dave]

Originally Posted by Dave Moll

Apologies if I'm missing something here, but could it be as simple as the leads being the wrong way round?

Yes, well sort of. The output socket from a cd player shares the -ve for both the left and right channels. If I swap the 'video' channel leads then it'll muddle the audio and video together

Originally Posted by ppppenguin

Either use a different CD player or an inverting amplifier stage between it and the televiser.

I've found one cd player out of three that manages to display a positive image. Unfortunately it's the only one without a line out socket, but it'll have do for now.

I'm, actually, staring in amazement at a test card 'F' . It's got a bit of a wobble and a, sort of, spirally line passing through it but it's not bad! If I can get it better I'll post a picture

Thanks
David

[Radio_Dave]

Oh well, It's now working really well. I wanted to post a picture of the test card image but I've found it impossible to take a, decent, photo so I've posted a couple of pictures of the contraption instead.

Ok, it's not rocket science and it's not pretty, but it certainly challenged me and I like it .

Now... what about a colour version!

David

[Panrock]

Very nice! Well done

Steve

[oldeurope]

Hi, I like it! Did you use a vinyl record as a Nipkow disc?

Kind regards,
Darius

[Radio_Dave]

No, I tried to make it from a 12" record, but I found it too difficult to drill the holes accurately

The Nipkow disc you see was purchased for only £9 from the NBTVA

Regards
David

[DrZarkov]

If you still want to make your own Nipkow-disc, I have several discs in a PDF-format on my website. Just download them and print them out. Not as perfect as the laser cut discs from the club or from Peter Yantczer, but they are working well (and don't cost anything;-).

http://www.retrocom.de/zarkov1.html