Baird Televisor NBTV NBTVA
proposal for a low priced kit which could be
marketed through Radio Shack in the US, or Maplin
in the UK, alongside the "Crystal
Radio" kits and "200 in 1 Electronics
Labs", and aimed at the $50 or £30 price
New Page Under Construction
Build a Working Baird
Use your computer printer to Print
Out a Nipkow Disk !
versions of the WAV picture files with Picture on
the Left channel & synchronous12½ Hz
Squarewave on the Right.
Right channel audio to the motor drive voltage to
synchronise the motor and get a steady picture!
- Click on the picture
above to see a large picture (720 x 720) of a Nipkow Disk for a 32 line Baird
- Print the picture from
Netscape or Internet Explorer.
- Glue it to some card and
cut around the black circle.
- Use a pin or miniature
drill to make holes in the card where the dots are. Don't
forget the centre hole.
- Get a miniature battery
operated fan (as sold in tourist shops) and pull the fan
- Attach the Nipkow Disk
where the fan blades were.
- Control the speed by
powering the fan from a 3-volt DC mains unit, connected
via a 10 ohm variable resistor.
- Get 10 or
more hyper bright LED's (any colour).
them all in parallel.
the group of LED's directly to the Loudspeaker output of
your computer's sound card.
- Play one
of the Baird WAV files from this site, and view the LED's
through the spinning disk.
If it all works
( ! ) you will now be watching genuine Baird system TV pictures
on your own home made Baird Televisor !
This is intended
to be the simplest possible demonstration of the Baird Televisor.
To make it even simpler you can :
- Use the
paper printout directly without the card.
about the variable resistor, just brake the motor with
your finger. Either way there is no synchronisation, so
the picture will roll and spin - a proper system for
synchronisation requires building an electronic servo
control which would make the demonstration much more
The light from
the LED's needs to be diffused evenly over an area about half an
inch by half an inch behind the disk :
different kinds of cloudy plastic.
alternative is to use a magnifying glass lens in place of
the diffuser. Mount a single LED behind the lens at
its focus, and the whole area of the lens will be lit,
brightly and fairly evenly, when seen from directly in
- The light
works much better if you put 3 volts d.c. across the LED
via a 47 Ohm resistor, with the sound card audio applied
across another resistor - see circuit diagram. (Use 4.7 Ohm
resistors if using 10 LEDs in parallel.)
The holes in
the disk should be of the right size.
The hole diameter
should be 1/32nd of the width of the picture scan:
- You can
estimate the right sort of size by eye.
- For more
precision, measure the difference in radius between the
inner and outermost holes on your printout, divide it by
32, and use a miniature drill of that size.
Click here for a high resolution
picture (2610 x 2610) of the Nipkow Disk.
You'll need to
save it to disk & use a graphics program like Paint Shop Pro
to print it. Get Paint Shop Pro version 3 from www.jasc.com
NBTV Picture Files in
Windows WAV Audio Format :
Right Click and "Save Target
save to Hard Disk
1.Central Strip of Test Card F
including the centre circle
2.Close up of Carol Hersee
in Test Card F
3.The letters N B T V
in a vertical column
Making the WAV
file longer using Windows Sound Recorder:
The WAV file
is much more useful if it's made longer by repeating the sequence
of frames as follows:
Recorder, this will be found in
Open the WAV
Press ctrl c,
then ctrl v.
This copies the
wav file, then pastes it to the end of itself, doubling the
Do this 5 times,
and you have quickly made the file 32 times longer.
Save the file. It
will now run for 2 minutes 44 seconds, containing 2048 frames,
and be 5 MegaBytes in size.
any WAV file can be made to repeat indefinitely in Windows Media
Player, this will be found in
Open the WAV
From the Edit
menu, select Options, and tick the "Auto Repeat" check
The pictures were generated as
Windows Bitmaps, then converted to WAV files on a PC using
"Cool Edit 96" by Syntrillium Software, available from www.syntrillium.com
- Each bitmap was made to
the NBTVA 32 line standard (Narrow Band TeleVision
- The sync pulse height is
30 percent, 77/255, or 4D(Hex).
- The sync pulse duration
chosen was 6/80 line period, 187.5 microseconds.
- The bitmap format chosen
was width 80 x height 32, 8 bit monochrome.
- This results in a 32 line
scan, with 2560 samples, bytes or pixels per frame.
This was converted to a WAV
file at a sampling rate of 32000 samples per second:
- It produces 32000/2560 =
12.5 frames per second, and
- A frequency spectrum with
a bandwidth of 16 kHz.
of data in the Windows Bitmap has been carefully studied to
ensure that the Baird pictures are:
Right Way Up
Sideways, ie they derive from 32 lines x 80 samples, not
80 lines x 32 samples
that they are compatible with the specification for the Baird and
NBTVA systems where:
- Line Scan
Direction is from Bottom to Top and
Scan Direction is from Right to Left
disk above is also made to this standard, and should be rotated ANTICLOCKWISE as viewed from the
print side. If someone
has the time to try playing these sound files into a proper Baird
Televisor, I would of course be interested to know the results!
Mail to email@example.com with any comments or
to other NBTV Sites
Narrow Bandwidth Television Association
British Amateur Television Association
Canadian Museum of Television
Click below to find out
How to draw the Nipkow Disk with