The end of the mass produced CRT

Ivan wrote on 06/12/2006 23:58:30:
"Graham" wrote in message
...

"Ivan" wrote in message
k...

"Graham" wrote in message
...

"
Is my memory playing tricks, or did the K7 use two line output valves
(plus a PY500 boost diode)
--

I'm pretty certain that it was the K70 chassis, a Swedish import, although
I
can't recall whether it had some kind of push-pull line-out put stage, but
I'm pretty certain as I said in a previous post, that the circuitry was
certainly slightly 'unconventional'.


IIRC a PL504 and a PL802 not push-pull though, some weird configuration.
--

Happy days Graham, I'm old enough to remember the days when I used to play
around with ancient TV's with mains derived EHT, and also exposed myself to
more X-rays from MW 6-2 projection CRT's than I care to remember!



Graham.
%Profound_observation%

Please may I broaden the reminiscences of this thread? Does anyone
remember the test films broadcast when 625 lines and colour TV were
being introduced? On BBC 2, I recall, one or more of these films
showed delightful young ladies attired in bikinis snorkelling amongst
coral reefs. If I could see these films again, it would make an old man
very happy.

Turps

Turps wrote:
Ivan wrote on 06/12/2006 23:58:30:
"Graham" wrote in message
...

"Ivan" wrote in message
k...

"Graham" wrote in message
...

"
Is my memory playing tricks, or did the K7 use two line output
valves (plus a PY500 boost diode)
--

I'm pretty certain that it was the K70 chassis, a Swedish import,
although I
can't recall whether it had some kind of push-pull line-out put
stage, but I'm pretty certain as I said in a previous post, that
the circuitry was certainly slightly 'unconventional'.


IIRC a PL504 and a PL802 not push-pull though, some weird
configuration. --

Happy days Graham, I'm old enough to remember the days when I used
to play around with ancient TV's with mains derived EHT, and also
exposed myself to more X-rays from MW 6-2 projection CRT's than I
care to remember!



Graham.
%Profound_observation%

Please may I broaden the reminiscences of this thread? Does anyone
remember the test films broadcast when 625 lines and colour TV were
being introduced? On BBC 2, I recall, one or more of these films
showed delightful young ladies attired in bikinis snorkelling amongst
coral reefs. If I could see these films again, it would make an old
man
very happy.

Turps

The one that sticks in my mind was the one about the Kariba Dam where people
were rescuing animals from the rising water.
--
Adrian

In article ,
Turps wrote:


Please may I broaden the reminiscences of this thread? Does anyone
remember the test films broadcast when 625 lines and colour TV were
being introduced? On BBC 2, I recall, one or more of these films
showed delightful young ladies attired in bikinis snorkelling amongst
coral reefs. If I could see these films again, it would make an old man
very happy.

These films came from the libraries of such companies as Shell, BP, Ford
and others. Who knows; copies may still exist.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

"charles" wrote in message
...
In article ,
Turps wrote:


Please may I broaden the reminiscences of this thread? Does anyone
remember the test films broadcast when 625 lines and colour TV were
being introduced? On BBC 2, I recall, one or more of these films
showed delightful young ladies attired in bikinis snorkelling amongst
coral reefs. If I could see these films again, it would make an old man
very happy.

These films came from the libraries of such companies as Shell, BP, Ford
and others. Who knows; copies may still exist.

--

http://www.bvws.org.uk/405alive/info...radefilms.html

From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

In article , Adrian A
writes
Turps wrote:
Ivan wrote on 06/12/2006 23:58:30:
"Graham" wrote in message
...

"Ivan" wrote in message
k...

"Graham" wrote in message
...

"
Is my memory playing tricks, or did the K7 use two line output
valves (plus a PY500 boost diode)
--

I'm pretty certain that it was the K70 chassis, a Swedish import,
although I
can't recall whether it had some kind of push-pull line-out put
stage, but I'm pretty certain as I said in a previous post, that
the circuitry was certainly slightly 'unconventional'.


IIRC a PL504 and a PL802 not push-pull though, some weird
configuration. --

Happy days Graham, I'm old enough to remember the days when I used
to play around with ancient TV's with mains derived EHT, and also
exposed myself to more X-rays from MW 6-2 projection CRT's than I
care to remember!



Graham.
%Profound_observation%

Please may I broaden the reminiscences of this thread? Does anyone
remember the test films broadcast when 625 lines and colour TV were
being introduced? On BBC 2, I recall, one or more of these films
showed delightful young ladies attired in bikinis snorkelling amongst
coral reefs. If I could see these films again, it would make an old
man
very happy.

Turps

The one that sticks in my mind was the one about the Kariba Dam where people
were rescuing animals from the rising water.

Have a look at

http://www.mb21.co.uk

and follow the links from there. There are a few vintage broadcast sites
around for the transmission end of it all. Also look up Testcard sites
they might have some links to those!....
--
Tony Sayer

In article , Graham
writes



Only this week I heard an item on Radio 5 about the recent (worldwide)
growth of organised criminal gangs, who are stealing millions of pounds
worth of copper wire and sometimes disabling whole railway systems

I heard that item on Radio 4.

A spokesman was reported to have said this wouldn't
put passengers at risk. I thought that was an arrogant statement
given the recent history of the industry.

I think you'll find railway signalling systems are designed to fail safe
i.e. when they develop a fault they signal or automatically make the
trains stop
--
Tony Sayer

tony sayer wrote:
I think you'll find railway signalling systems are designed to fail
safe i.e. when they develop a fault they signal or automatically make
the trains stop

Failsafe systems are only failsafe when all the possible failure modes have
been considered. One of the 'failsafe' mechanisms used in railway signalling
is to divide the track into sections ('blocks'), with each block protected
by a signal at its entrance. If the block is occupied by a train, the signal
automatically defaults to red, preventing another train from entering
(assuming - in the absence of other automated mechanisms - that its driver
is awake!). The safety of such a system depends on being able to detect the
presence of a train on a piece of track. One way of doing this is to pass a
small current through the rails, the presence of which is required to enable
the 'proceed' signal. The leading wheelset of a train entering that section
of track will shortcircuit the current, causing the signal to default to
'stop'. Any other failure of the current, for whatever reason, will also
cause the signal to default to 'stop'. Failsafe? Not quite. The wrong kind
of leaves on the track can form an insulating paste around the wheels...

[I should point out that I do not know what mechanisms are used in current
state-of-the-art railway signalling systems. I do know that the general
principles I've given are correct, and that BR had problems with
disappearing trains on their computerised signalling systems in the 1990's,
because of leaves. Failsafe systems sometimes don't.]

John wrote:
Looking to the future I think that the next generation will look back at in
amazement that the colour CRT could be mass produced so cheaply and to such
a high standard. I must confess that even though I understand the theory of
the shadow mask, the 3 guns and the phosphor dots I just cannot get my mind
around how the mass production has been developed and how it can have
developed to such a high standard.


I going to rant now--

I think the answer to the cost is that they are not produced to a high
standard. Over the years we had a competition between western companies
who had pride in their work and products but didn't like change, and
with far eastern companies who first applied advanced engineering
techniques to the products and design processes (Japanese) combined with
a very obedient workforce this enabled them to produce high quality
goods at ever decreasing costs.

This worked during the 80s and 90s when the consumer industry earned a
reputation for quality that was and still is taken for granted. We also
had developing (and now developed) countries who tried to do the same
only with much less pride in their work, subsidies from their
governments (to cover EU duty) and less experience/education. If they
didn't know why a product needed a certain type of high spec material it
didn't get it and so the product failed early for a reason they didn't
understand (my cheap bedroom TV whines badly after 13 months). They
also now test much less than they used to as its easy to design a
product based on the key component suppliers reference design and make
it work (albeit not very well).

Supermarkets are now dealing TV/STB/PVRs etc and they simply put in
enough margin to cover them for a high degree of returns, they insist
on a full no quibble returns agreement with the supplier (retail chains
aren't much better). There are many suppliers and this is why you see
the cheap products are never the same brand as they have had high
returns and the purchaser has moved on to someone else (or they find
another supplier for their inhouse brand). The competitive market is
now driving quality down due to an imbalance of power.
Retailer's buyers only care about the price and not quality, so if you
are a good quality supplier they want the same price as the
subsidised/low quality/royalty infringed rubbish you are competing with.

Having said all that this is what consumers want, disposable products
that just about work for a few years and they will buy something better
when they can afford it. This works because now people who couldn't
afford good stuff now can afford the ****e (bigger market), but also the
people who can afford the good stuff can't tell the difference and buy
the ****e too. Possibly also assisted by the fact that most brands mean
very little these days except for to the few in the know, as products
are design, manufactured and sold by different companies.

Economically its fine (possibly if you not a western supplier), but
environmentally its a disaster.

The sale of goods act was supposed to improve quality and now covers 6
years responsibility for the seller but none of them seem to accept that
and are still using the 1 year rule.

Ok there are good brands out there that do everything, but actually
their market share is small compared with the ****e.

Rant over
--
Tony

Laurence Taylor wrote:

Hands up those who remember "Its the tube that makes the colour"

One hand here! (Only just). Be nice to see it again, in fact.

And who remembers "clean and prime, coat, wrap and lay" and "switch-off,
isolate, dump, earth" ...?

And, much more recently, the BBC windmills film in the early days of DTT.

--
Andy

In article , Pyriform
writes
tony sayer wrote:
I think you'll find railway signalling systems are designed to fail
safe i.e. when they develop a fault they signal or automatically make
the trains stop

Failsafe systems are only failsafe when all the possible failure modes have
been considered. One of the 'failsafe' mechanisms used in railway signalling
is to divide the track into sections ('blocks'), with each block protected
by a signal at its entrance. If the block is occupied by a train, the signal
automatically defaults to red, preventing another train from entering
(assuming - in the absence of other automated mechanisms - that its driver
is awake!). The safety of such a system depends on being able to detect the
presence of a train on a piece of track. One way of doing this is to pass a
small current through the rails, the presence of which is required to enable
the 'proceed' signal. The leading wheelset of a train entering that section
of track will shortcircuit the current, causing the signal to default to
'stop'. Any other failure of the current, for whatever reason, will also
cause the signal to default to 'stop'. Failsafe? Not quite. The wrong kind
of leaves on the track can form an insulating paste around the wheels...

[I should point out that I do not know what mechanisms are used in current
state-of-the-art railway signalling systems. I do know that the general
principles I've given are correct, and that BR had problems with
disappearing trains on their computerised signalling systems in the 1990's,
because of leaves. Failsafe systems sometimes don't.]



Thanks for the lecture about track circuiting...

Look up TPWs
--
Tony Sayer