27 Feb
2012
27 Feb
'12
3:36 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org
[mailto:cctalk-bounces at classiccmp.org] On Behalf Of Tony Duell
Sent: 27 February 2012 20:49
To: cctalk at classiccmp.org
Subject: Re: UK versus US monitor question
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.
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.
Perhaps as amateur sync gen, there is reference to mains sync here:-
http://vss.pl/cq_tv/cq-tv31.pdf
But I think that's for the sync generation at the camera. I did think the
Pye V4 used mains to sync frequency (NOT PHASE) but when I looked it up it
didn't. Then I also recall the horrid problems most TV's of that age had
with frame sync. I seem to remember one of the Apollo moon shots being
described in terms of a number of TVs with no adjustment to frame sync.
It used to be the case that TVs synced to the mains
frequency but I don't
Was it? -tony