On 20/02/2014 11:51, gareth wrote:
"AndyW" wrote in message
...
On 19/02/2014 09:32, gareth wrote:

LED or nitro-benzine as the polariser?
Polariser?

To my eternal regret, because I disposed of them 38 years ago, I had a
pile of "Amateur Wireless" from the 1930s within which were designs
for mirror-drum scanners, and the modulation was not by a neon light
but with a constant light source which was then modulated by a series
of polarising filters, with one being variable to rotate the polarisation.

ISTR (38 years ago!!!) that the liquid used was nitro-benzene

OK I follow you now. I had a quick google and found out about
nitrobenzene and modulating polarisation. Never heard of it before. Live
and learn.

My original set up was as simple and agricultural as they come, vinyl
LP, scrap motor from a cassette player, Neon attached to am amplifier
behind the 'screen' and a camera made from a lens and an LDR recording
onto a cassette player - the bandwidth was low enough to record on audio.

My latest televisor was made from a circle of black plastic spinning on
a hand fan with a very small torch behind it modulated by the sound from
a small mp3 player. It all folds up and fits in a pocket.

Andy