On Thu, 4 Sep 2003 03:50:04 -0700, Watson A.Name - "Watt Sun"
wrote:

Underneath the glass was a thick tray with grooves
cut (or cast) into it in the shape of the letters EXIT. Each groove
had a pale yellowish rod laying in it, a bit thicker than a pencil
lead. My guess is that this is some kind of phosphorescent material
that glows when light from flames from a fire are hitting it. There
is _no_ power to the sign.


Could it have been a tritium source? I've seen them to be yellowish
glass vessels. It would be hard to see it glow without cupping your
hand over it i think.

In article ,
mentioned...
On Thu, 4 Sep 2003 03:50:04 -0700, Watson A.Name - "Watt Sun"
wrote:

Underneath the glass was a thick tray with grooves
cut (or cast) into it in the shape of the letters EXIT. Each groove
had a pale yellowish rod laying in it, a bit thicker than a pencil
lead. My guess is that this is some kind of phosphorescent material
that glows when light from flames from a fire are hitting it. There
is _no_ power to the sign.


Could it have been a tritium source? I've seen them to be yellowish
glass vessels. It would be hard to see it glow without cupping your
hand over it i think.

That sounds like it might be what's in the rods. I didn't try to see
if it glowed when I darkenwed the area. I know that the H bombs that
were made during the cold war years are losing srength because the
tritium in them is decaying, so tritium doesn't last all that many
years. That blgd is about ten years old.


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10 or 12 year half-life on tritium

On Thu, 4 Sep 2003 23:07:09 -0700, Watson A.Name - "Watt Sun"
wrote:

In article ,
mentioned...
On Thu, 4 Sep 2003 03:50:04 -0700, Watson A.Name - "Watt Sun"
wrote:

Underneath the glass was a thick tray with grooves
cut (or cast) into it in the shape of the letters EXIT. Each groove
had a pale yellowish rod laying in it, a bit thicker than a pencil
lead. My guess is that this is some kind of phosphorescent material
that glows when light from flames from a fire are hitting it. There
is _no_ power to the sign.


Could it have been a tritium source? I've seen them to be yellowish
glass vessels. It would be hard to see it glow without cupping your
hand over it i think.

That sounds like it might be what's in the rods. I didn't try to see
if it glowed when I darkenwed the area. I know that the H bombs that
were made during the cold war years are losing srength because the
tritium in them is decaying, so tritium doesn't last all that many
years. That blgd is about ten years old.

On Thu, 04 Sep 2003 14:36:25 -0700, Lizard Blizzard
wrote:

I think you have that backwards. Back then, the radio and TV sets were
still using 5U4 TOOBS for rectifiers, whereas the electrical world
already had equipment with SCRs up to the size of hockey pucks that
could handle up to 1200 amps (http://www.cehco.com/sda.htm), and 1N1184
series of 35 amp stud mount rectifiers were common in equipment


That could be. I was just a young pup in the 60s, but I remember the
diodes were the top-hat kind that didn't fit into lamp-saver sockets.
I don't recall seeing anything other than variacs for lamp dimmers
either.

In article ,
mentioned...
Sounds like a great class, where you have to block the door to keep the
students from leaving. What was the class and who sponsored it? A
mandatory safety class perhaps?

It's a temporary setup for registration, not a class. We have a dozen
or more PCs set up for students to register for classes. When they're
done they go over to the next room to pay their fees.
Understand, Rubber Band?

Roy Lewallen, W7EL

Watson A.Name - Watt Sun wrote:

I gotta tell you what happened at work last week. The head of
security came over and told us that someone had complained that one of
our tables was blocking the door (it's a temporary setup). The head
of registration told him that she put it there to keep the students
from leaving. The security guy says, but that's an emergency exit,
see that sign up there?

So she says, oh, ok. Well, then, can we move the sign?

:-)))


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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 at hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@ u@e@n@t@@

In article ,
mentioned...
On Thu, 04 Sep 2003 14:36:25 -0700, Lizard Blizzard
wrote:

I think you have that backwards. Back then, the radio and TV sets were
still using 5U4 TOOBS for rectifiers, whereas the electrical world
already had equipment with SCRs up to the size of hockey pucks that
could handle up to 1200 amps (http://www.cehco.com/sda.htm), and 1N1184
series of 35 amp stud mount rectifiers were common in equipment


That could be. I was just a young pup in the 60s, but I remember the
diodes were the top-hat kind that didn't fit into lamp-saver sockets.
I don't recall seeing anything other than variacs for lamp dimmers
either.

When I was in the army in the late '60s we were constantly replacing
those top hat rectifiers in the CRTs for the radars. In each lead,
they had 3 or 4 1N547s, each rated 600V, 1/4A, in series, with a cap
across each one, to rectify the B+. The deflection plates used pretty
high B+ so the diodes were always failing. If we would have been
smarter, we wwould have put more in series, but then Military
Intelligence was an oxymoron. :-P

They used to use fuse holders to hold the top hats and help keep them
cool. Later they came out with a metal package that was a bit longer
and smaller in diameter, with no 'hat brim', so it could fit into a
button that would fit into the lamp socket.

We should find out from one of the 'Semiconductor Antiquities Experts'
when the 1N4002 series of epoxy case rectifiers caame out. My 1969
Motorola manual has them in it, and uses them as a substitute for the
top hat rectifiers. The 1N4002 series must have been out in the mid
'60s or maybe earlier. Someone recently mentioned Poly Paks. Those
surplus sales companies used to sell grab bags full of those old top
hat diodes, probably slightly leaky or lower voltage than usual. Same
with the old TO-5 germanium transistors. Today those guitar FX nuts
would drool over a bag of decent quality Ge transistors. :-P' ' '


--
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###Got a Question about ELECTRONICS? Check HERE First:###
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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 at hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@ u@e@n@t@@

Stepan Novotill wrote:
10 or 12 year half-life on tritium


Oh that's pretty good. That link earlier said "guaranteed for 6 months,"
they made it sound like it would be good for a year or so, was wondering why
they were that expensive if they only lasted a year.

030904 1736 - Lizard Blizzard wrote:

Back then, the radio and TV sets were
still using 5U4 TOOBS for rectifiers, whereas the electrical world
already had equipment with SCRs up to the size of hockey pucks that
could handle up to 1200 amps


Imagine the size of the heatsink for that...

indago wrote:
030904 1736 - Lizard Blizzard wrote:

Back then, the radio and TV sets were
still using 5U4 TOOBS for rectifiers, whereas the electrical
world already had equipment with SCRs up to the size of
hockey pucks that could handle up to 1200 amps


Imagine the size of the heatsink for that...

The heatsink is "live" for that style rectifier. It has to be tightened
onto the rectifier (sandwitched) using several bolts. There's acually a
compression rating - if a certain static force is not present during
operation, it will explode...

In article ,
mentioned...
030904 1736 - Lizard Blizzard wrote:

Back then, the radio and TV sets were
still using 5U4 TOOBS for rectifiers, whereas the electrical world
already had equipment with SCRs up to the size of hockey pucks that
could handle up to 1200 amps


Imagine the size of the heatsink for that...

Things with big SCRs, like motor controllers, don't have a heatsink as
you would think of it. They use a square tube with fins pointing into
the cavity, and fans on the end.


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###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/e...s/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 at hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@ u@e@n@t@@