| Baird
Televisor Kit This is a proposal for a low priced kit which could be marketed through Radio Shack in the US, or Maplin in the UK. It would be sold alongside the "200 in 1 Electronics Lab" and the "Crystal Radio" kit, and should be aimed at the same price bracket:
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The Kit would contain 6 basic parts:
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The Disc has 32 small
holes arranged in a spiral and spins at 12.5
revolutions per second in front of the LEDs,
which back illuminate one portion of the disc, at the
position of the number "3" on
a clock face. When the light varies rapidly in
brightness, the disc produces a small television
picture by scanning the holes rapidly past the
backlight. This is how the first mechanically scanned
televisions worked in the 1920's and 30's. * LED's should be in 2 colours, for example 3 x Orange-Red, plus 3 x Blue-Green. At no extra cost, this produces a much more visually exciting experience by taking advantage of the fact that the signal sources from which the kit will get it signals will be stereo audio sources, a PC sound card or CD player. All Televisor pictures can be made with 2 contrasting colours driven from the Left and Right audio channels respectively. |
Source Pictures:
These come from a CD and a special internet
site. The kit could be sold with a CD containing
as many as 70 example pictures which would each play for 1
minute. The instructions would include an internet
address from where new pictures could be downloaded. The Televisor
file format - audio pictures - is quite unique
so this should present no "safe surfing" problems. It
may also be worth investigating PC software to convert regular
digital photos from any PC into a 2-colour Televisor
audio picture. This can be done with standard software
which is already available, for example "Paint Shop
Pro" and "Cool Edit Pro / Adobe Audition" when
used together. It may be possible to get a software house to
write a specialist program which combines the necessary parts of
the two, and license it for the Televisor Kit.
Other considerations:
Synchronisation: This is very important, as
without it you do not see a meaningful picture. It will be
necessary to include some form of rudimentary "sync
seperator" and motor drive amplifier to kick the motor 12.5
times a second from the pulses which are built in to the
Televisor audio pictures. This should be enough to make for a
viewable picture when used alongside the manual speed control
knob.
Instructions:
These should include educational references to the history of the
development of television, and describe how the kit is a genuine
reproduction of the first real TV sets like the Baird Televisor
in Britain, or the Jenkins Radiovisor in the US!
Safety:
There should be few safety problems due to the low speed (750
rpm) and light weight (a few grammes)
of the disc, which would have no more energy in use than a
typical battery operated handheld fan. Nevertheless there should
be a warning not to play with disc while it is spinning, or try
to stop it by touching the edge of the disc. The disc should be
made of thin plastic with some flexibilty, and the rim should
have a blunt profile.
Age:
I would suggest labelling the kit for "ages 12 and
above"
I would be pleased to act as a consultant
for any manufacturer who is interested in making the kit.
Contact me at stephen@sptv.demon.co.uk
General information:
A great deal of General information about Baird Televisors can be
found at the Narrow Bandwidth Television Association,
NBTVA. Website www.nbtv.org The use
of a 32 hole disk and a speed of 12.5
revolutions per second is in accordance with the NBTVA
standard for 32 line television, which is itself
very close to the standards originally used by pioneers such as Baird.
This standard has been optimised for the best small picture
performance possible within the bandwidth of standard audio
systems.
Baird Televisor Kit page online since 22nd
March 2004.
Last updated 22nd January 2008.
