NBTV Television Project Help

[Steve Anderson]

I hope you are aware that a NBTV monitor cannot display a normal 525 or 625 video signal, so no direct VHS/game console/DVD will work. NBTV files are stored usually as audio .wav files or similar uncompessed format as the bandwidth compared to standard TV is so low.

Standard definition TV has 525 or 625 lines, NBTV only has 30 or 32 (mostly). Also the scanning directions are reversed and rotated (for want of a better word). It's usually also monochrome.

Steve A.

[reshiram202]

So is it still possible to get some sort of image on this disk?

[reshiram202]

Ah that makes sense. Is it possible to make a real time 525 to 32 converter? For example, say I want to play a VHS tape with my mechanical televisor. I hook up the rca cables into a converter which takes that signal and transfers it to audio and plugs into the televisor to display the image. Would it work with the right circuitry?

[DrZarkov]

Here is my scanning disk made out of cardboard. Is it good? Is it bad? I don't know. I reeaally don't want to restart but if I really need to I will.

Do I see it right? You took corrugated cardboard? That will of course not work! The material for the disc must be as thin as possible, but also strong, in order that the disc will not wobble. The apertures in the disc are called "pinholes", not "nail-holes". Guess why. A little overlap will not be that terrible (but not really good), but an overlap of several lines will not work. I used a black plastic-sheet from the backside of a plastic-folder for the disc. I've printed the disc in PDF-format on paper, put that print with some Scotch-tape on the plastic, an punched the holes with a pin. The result is quite good, the pictures a recognisable. You can find the PDF here: http://www.zarkovision.de/nbtv-disc1.pdf
Or if you prefer a disc with sync-holes (if you want to use automatic synchronisation of the picture): http://www.zarkovision.de/nbtv-disc2.pdf

Those discs are in the "club standard" with 32 lines, which looks much better than it sounds compared to modern days 1080 lines.

[DrZarkov]

Ah that makes sense. Is it possible to make a real time 525 to 32 converter? For example, say I want to play a VHS tape with my mechanical televisor. I hook up the rca cables into a converter which takes that signal and transfers it to audio and plugs into the televisor to display the image. Would it work with the right circuitry?

Yes and no. That converter will be very complicated. You can buy them for around 170 US$. Much easier (and cheaper) it would be to use a software for real-time conversion. For windows you'll find software here: http://users.tpg.com.au/users/gmillard/nbtv/nbtv.htm As an input you can use any videos from your PC, but you can also connect a camera or VHS-recorder, if your computer has the necessary inputs. The output for your mechanical TV is the sound card of your PC: Left channel: picture, right channel: sound.

[Klaas Robers]

Jimmy, very good that you gave a photo of the disc you made. Now we can help you.

The reason that the holes should be pinhole small is that, when you rotate your disc, keeping the center hole on the same place, you will see that the holes that you drilled will descibe the 32 lines of what will become your picture. Each line will have the width of the size of your holes. With these large holes you will see that the lines will overlap each other very much. That results in a very unsharp picture.

Optimally the lines should just touch each other, that is for square holes, and for round holes (much easier to make) they shoud overlap 15% of the width. Then each hole describes only its own line and not very much of the neighbouring lines as well. That is also the reason why the positioning of the holes is so important.

But don't throw away your disc yet and yes continue with your disc monitor. It will give you some form of picture although very unsharp. Then the solution is to make the holes smaller, pinhole size. You can produce that in the following way, but after you have seen that it works anyway, and gives your unsharp picture:
- clip small squares of aluminium kitchen foil, 1 cm x 1 cm,
- glue these squares over the large holes that you have made,
- make a new print out of the .pdf of dr. Zarkov,
- position that carefully over the old large holes,
- may be you have to do that positioning before you glued the squares,
- and mark carefully the position of the print-out, such that you can find this back after the foil glueing,
- and pinch with a sewing nail carefully through the paper and the aluminium foil.

Now you have got a disc with very small holes and which is extremely thin at the place of the holes. The remaining thickness or thinness of the disc of little importance. This disc is even better than the pinched grammophone record previously suggested.

But do this AFTER you have seen some form of picture from your existing disc. It is better to improve already working things than to make everything perfect from the beginning. Work step by step.

[Klaas Robers]

Jimmy, we talk of video, although it is audio. A video signal is an electrical signal (varying voltage) from which you can make a picture. An audio signal is an electrical signal, from which you can make sound. However they are both electrical signals.

Making a picture requires some form of monitor or TV-set. This is for HDTV, 1080 lines, or standard TV, 625 lines or 525 lines and also for NBTV, 32 lines or about that.

Making sound requires a loudspeaker, headphones or earphones, and in most cases an amplifier. You may know that sound, music consists of low tones = basses, middle tones and high tones = treble. Amplifiers can boost them or squeeze them. You will have used that. All tones have a frequency. We measure that in hertz (Hz). Low tones have a low frequency, say 100 Hz, middle tones are about 500 to 1000 Hz and high tones go from 5000 to 20 000 Hz. We cannot hear higher tones than 20 000 Hz (= 20 kilohertz, kHz), that is YOU can't hear them; girls normally hear until 22 000 to 25 000 Hz, and me, I am 5 times as old as you are, can't hear higher than about 9 kHz. When you grow older this ceiling comes gradually down.

The CD is designed to hold sound. It can cover frequencies from 20 Hz to 20 kHz. Twice, once for left and once for right. That is more than good enough for music. CD is meant for audio.

Television needs much higher frequencies. The video signals for standard TV (625 lines) go up to 5 MHz (5 000 kHz or 5 000 000 Hz), and High Definition even to 25 MHz. Our NBTV system with just 32 lines and 12.5 frames (pictures) per second needs no more than 10 kHz. That is the reason that a video signal for NBTV can be stored onto a CD, as if it were a sound signal. In practice we store it on the left channel, while the right channel is used for (mono) sound next to the pictures. When you play such a disc on your stereo installation, you will hear the sound of the video signal at your left, and the sound of the sound signal on your right.

So you don't need a VHS machine to play back your NBTV video + sound. A CD-player will do. That having said, you can also play back NBTV video + sound directly from your computer, when you have it in the form of a "wave file" (.wav). These are large files that you generally compress into an mp3 file. However when doing that it is fine for the sound part, but it will generally ruin the video channel. MP3 makes use of imperfections of our hearing system (= ears), that cannot be applied to video signals.

I hope this will clear up a few things for you. Good luck!!

[McGee2021]

You might think of me as crazy, but I have no intention of using repro disks. If I want to design anything electronic, I will never use a kit. I did consider the MUTR kit but the videos on it made me think otherwise. I will post a picture of my disk sometime.

5 years old??? Wow. I got into electronics when I was about 10! What did your first televisor look like?

it was a simplified baird televisor. the lens disk i hope to make will look like the western empire state. i also restore vt radios, and will install two on the tv . i have built about 9 transmitters, so i hope it would be wireless

[reshiram202]

Jimmy, very good that you gave a photo of the disc you made. Now we can help you.

The reason that the holes should be pinhole small is that, when you rotate your disc, keeping the center hole on the same place, you will see that the holes that you drilled will descibe the 32 lines of what will become your picture. Each line will have the width of the size of your holes. With these large holes you will see that the lines will overlap each other very much. That results in a very unsharp picture.

Optimally the lines should just touch each other, that is for square holes, and for round holes (much easier to make) they shoud overlap 15% of the width. Then each hole describes only its own line and not very much of the neighbouring lines as well. That is also the reason why the positioning of the holes is so important.

But don't throw away your disc yet and yes continue with your disc monitor. It will give you some form of picture although very unsharp. Then the solution is to make the holes smaller, pinhole size. You can produce that in the following way, but after you have seen that it works anyway, and gives your unsharp picture:
- clip small squares of aluminium kitchen foil, 1 cm x 1 cm,
- glue these squares over the large holes that you have made,
- make a new print out of the .pdf of dr. Zarkov,
- position that carefully over the old large holes,
- may be you have to do that positioning before you glued the squares,
- and mark carefully the position of the print-out, such that you can find this back after the foil glueing,
- and pinch with a sewing nail carefully through the paper and the aluminium foil.

Now you have got a disc with very small holes and which is extremely thin at the place of the holes. The remaining thickness or thinness of the disc of little importance. This disc is even better than the pinched grammophone record previously suggested.

But do this AFTER you have seen some form of picture from your existing disc. It is better to improve already working things than to make everything perfect from the beginning. Work step by step.

Thanks for the tip! Glad to see I can still make this work without having to start all over again.

[reshiram202]

Jimmy, we talk of video, although it is audio. A video signal is an electrical signal (varying voltage) from which you can make a picture. An audio signal is an electrical signal, from which you can make sound. However they are both electrical signals.

Making a picture requires some form of monitor or TV-set. This is for HDTV, 1080 lines, or standard TV, 625 lines or 525 lines and also for NBTV, 32 lines or about that.

Making sound requires a loudspeaker, headphones or earphones, and in most cases an amplifier. You may know that sound, music consists of low tones = basses, middle tones and high tones = treble. Amplifiers can boost them or squeeze them. You will have used that. All tones have a frequency. We measure that in hertz (Hz). Low tones have a low frequency, say 100 Hz, middle tones are about 500 to 1000 Hz and high tones go from 5000 to 20 000 Hz. We cannot hear higher tones than 20 000 Hz (= 20 kilohertz, kHz), that is YOU can't hear them; girls normally hear until 22 000 to 25 000 Hz, and me, I am 5 times as old as you are, can't hear higher than about 9 kHz. When you grow older this ceiling comes gradually down.

The CD is designed to hold sound. It can cover frequencies from 20 Hz to 20 kHz. Twice, once for left and once for right. That is more than good enough for music. CD is meant for audio.

Television needs much higher frequencies. The video signals for standard TV (625 lines) go up to 5 MHz (5 000 kHz or 5 000 000 Hz), and High Definition even to 25 MHz. Our NBTV system with just 32 lines and 12.5 frames (pictures) per second needs no more than 10 kHz. That is the reason that a video signal for NBTV can be stored onto a CD, as if it were a sound signal. In practice we store it on the left channel, while the right channel is used for (mono) sound next to the pictures. When you play such a disc on your stereo installation, you will hear the sound of the video signal at your left, and the sound of the sound signal on your right.

So you don't need a VHS machine to play back your NBTV video + sound. A CD-player will do. That having said, you can also play back NBTV video + sound directly from your computer, when you have it in the form of a "wave file" (.wav). These are large files that you generally compress into an mp3 file. However when doing that it is fine for the sound part, but it will generally ruin the video channel. MP3 makes use of imperfections of our hearing system (= ears), that cannot be applied to video signals.

I hope this will clear up a few things for you. Good luck!!

Thanks for the clarification. So how would I go about hooking up my computer to the televisor? Would it just use a regular USB to AV cord?

[McGee2021]

I think going to the nbtva website would answer many of your questions.

You can find it here:
http://www.nbtv.org/

[Klaas Robers]

No no Jimmy, of course not. The NBTV video signal is a signal that is compatible with audio. If you play back the .wav file the output is coming out of the earphone socket of your PC. That is: from the left channel. I think it is the tip of the earphone plug. If you have loudspeakers connected you will hear the video signal. It is just like sound, remember?

For a demonstration of this:
- go to the NBTV.org website: http://www.nbtv.org,
- scoll the home page completely down,
- and click on the bottom link: "the characteristic NBTV sound."
- read that page and you can hear the sound,
- by clicking on a yellow button,
- although what you hear it is a compressed MP3 file;
- as well as down load a much better .wav file.

Experiment with this. It will open your eyes (and your ears).

Good luck.

[reshiram202]

Scanning disk mark II. This time I used one of my Dad's brad nails to punch the holes. I hooked it up to a motor and it barely held on. So I just spin it on a screwdriver using my hand. Very noticeable difference in quality. I used some LEDs to test the quality. Looks good so far to me. Gonna get me a fan motor and speed control to spin the disk.

[McGee2021]

This may sound strange, but i have a concept for a new type of disc. The disc would be square, with a square set of pinholes on the interior. When spinning, it would essentially make a zigzag pattern to make a image, but it wouldn't be a "square" spiral though. Just a thought.

[reshiram202]

This may sound strange, but i have a concept for a new type of disc. The disc would be square, with a square set of pinholes on the interior. When spinning, it would essentially make a zigzag pattern to make a image, but it wouldn't be a "square" spiral though. Just a thought.

I feel like I heard of a scanning disk like that somewhere. Interesting idea though.