27 Feb
2012
27 Feb
'12
3:14 p.m.
On 2/27/2012 1:48 PM, Tony Duell wrote:
A long time ago...
OK, I am sceptical. What do you mean by a 'long time ago'?
Unti lthe coming of the National Grid, different areas would be supplied
with mains at slightly differnet frequencies (even assuming it was
supposed to be nominally 50Hz), and therre would eb no phase relationship
at all. So usign that for any form of TV synchronisation is a non-starter.
So that really limits us to post-WW2 TVs. The oldest book of schematics I
have is dated 1953, but it contains models going back to 1948. Not one
attempts to derrive the vertical sync signal from the mains as far as I
can see.
I think it goes back more to the spinning disk TV format from the late 30's.
http://www.tvhistory.tv/index.html Dig here for more history on TV
It used to be
the case that TVs synced to the mains
frequency but I don't
Was it? But I am a scientist... So while I have not found such
a TV, I an't say
they don't exist. So I would ask you to state the make and model of one
or more TVs that derrived the vertcal sync signal from the mains, so that
I can track down the scheamtics and see what they did.
-tony
Ben.