Stepan Novotill wrote:

On Wed, 3 Sep 2003 03:31:59 -0700, Watson A.Name - "Watt Sun"
wrote:


The bulb savers that I used back in the '70s were varistors. They
slowed down the turn-on of the light. They were low resistance when
warm, and high when cold. There was no diode.


These were actually Metal Oxide NTC thermistors back then (not Metal
Oxide Varistors), since silicon diodes were at that time just a
curiosity in the "ELECTRICAL" world as opposed to the "ELECTROMICS"
world.

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
(http://dkc3.digikey.com/PDF/T032/0547.pdf). And your average battery
charger had diodes in it, it just so happened that the manufacturers
were still stuck back in the "Stink Stack" days, still using selenium
rectifiers.

The problem with the Diode or the NTC solution, is that it does
nothing to save the bulb from line transients.

The NTC worked well because most bulb failures occurred during turn-on.

[snip]

Stepan

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

The NTC worked well because most bulb failures occurred during turn-on.

But soft-starting does not extend bulb life significantly in most
cases. Voltage reduction is what does the trick.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

I think that furthermore, the few volts lost in the NTC aslo goes a
long way to extending bulb life, regardless.

s

On Thu, 04 Sep 2003 22:53:34 GMT, Spehro Pefhany
wrote:

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

The NTC worked well because most bulb failures occurred during turn-on.

But soft-starting does not extend bulb life significantly in most
cases. Voltage reduction is what does the trick.

Best regards,
Spehro Pefhany

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...
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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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.


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@ h@e@r@e@@
###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@@

Watson A.Name - Watt Sun wrote:

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.

And some of them use water-cooled aluminum "cold plates", rather than fans.

Bob Weiss N2IXK