modern christmas tree lights ....... a mystery to me

J

JohnMB

Guest
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.
 
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.
Click to expand...
Probably cause It's not a series circut.
 
"rstlne" <.@.> writes:

Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

Probably cause It's not a series circut.
Click to expand...
No, it probably is. There is an "anti-fuse" in there that shorts out when
more than a specific breakdown voltage appears across it. This will happen
when the lamp burns out. Of course, when a lamp burns out and shorts out,
slightly more voltage will be present across all the other lamps. When enough
lamps burn out and short, the entire string will go up in one spectacular
display of fireworks. Hopefully, there is a properly sized fuse in series
with the string! :)

Examine the lamp that doesn't light. You'll find a bar across the filament
leads. That's the short. When the lamp is alive, it's insulated from the
filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the string
will go out.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

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Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.
Click to expand...
You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP
 
On Sat, 20 Dec 2003 20:33:37 -0600, "Ralph Wade Phillips"
<ralphp@techie.com> wrote:

Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP

So why don't they wire them in parallel, to begin with?
Click to expand...

Dwight.
 
<sponger09@comcastONOSPAM.net> wrote in message
news:mg5auvkrhiie92b6v8dp4f9qpm9qnhjrj7@4ax.com...
On Sat, 20 Dec 2003 20:33:37 -0600, "Ralph Wade Phillips"
ralphp@techie.com> wrote:

Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP

So why don't they wire them in parallel, to begin with?

Dwight.
Click to expand...

Cause 50 lights in series means 2.5v per light (US)..
Power saving
I had to revisit the idea that they were done in parallel, Some of your
outside lights are still done in parallel but the small ones arent
apparently.. I sure thought it was all moved away from series, but I guess I
had it backwards
 
Sam's correct as usual. :) I managed to find a web page which gives
a bit more info about this subject I was always curious about too:
http://www.psrc-online.org/how/howthingswork.html

Bob



Sam Goldwasser <sam@saul.cis.upenn.edu> wrote:
No, it probably is. There is an "anti-fuse" in there that shorts out when
more than a specific breakdown voltage appears across it. This will happen
when the lamp burns out. Of course, when a lamp burns out and shorts out,
slightly more voltage will be present across all the other lamps. When enough
lamps burn out and short, the entire string will go up in one spectacular
display of fireworks. Hopefully, there is a properly sized fuse in series
with the string! :)

Examine the lamp that doesn't light. You'll find a bar across the filament
leads. That's the short. When the lamp is alive, it's insulated from the
filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the string
will go out.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
Click to expand...
 
<sponger09@comcastONOSPAM.net> wrote in message
news:mg5auvkrhiie92b6v8dp4f9qpm9qnhjrj7@4ax.com...
On Sat, 20 Dec 2003 20:33:37 -0600, "Ralph Wade Phillips"
ralphp@techie.com> wrote:

Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP

So why don't they wire them in parallel, to begin with?

Dwight.
Click to expand...
Because it's very hard to make efficient low wattage filaments with a
voltage as high as 120v (or 240 even in other parts of the world), it's much
easier to use a string of low voltage bulbs in series. Larger C7 and C9
strings use 120v bulbs in parallel.
 
On Mon, 22 Dec 2003 04:02:31 GMT, "James Sweet"
<jamessweet@hotmail.com> wrote:

sponger09@comcastONOSPAM.net> wrote in message
news:mg5auvkrhiie92b6v8dp4f9qpm9qnhjrj7@4ax.com...
On Sat, 20 Dec 2003 20:33:37 -0600, "Ralph Wade Phillips"
ralphp@techie.com> wrote:

Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP

So why don't they wire them in parallel, to begin with?

Dwight.

Because it's very hard to make efficient low wattage filaments with a
voltage as high as 120v (or 240 even in other parts of the world), it's much
easier to use a string of low voltage bulbs in series. Larger C7 and C9
strings use 120v bulbs in parallel.
Click to expand...
It's also cheaper to make safe low voltage sockets.
 
To get back to the original question, there is a small wire wrapped
around the base of the wires supporting the filament. That wire has
very thin insulation. When the bulb burns out, the filament goes
open, and the entire 120 V (in the USA) is across the two supporting
wires. That voltage breaks down the insulation, the sire shorts
(effectively) the two support wires, and the circuit is once again
completed. IF you have a series string with only 10 to 20 lights in
the circuit, when one bulb burns out and shorts, the increased voltage
across the remaining lights is increased appreciably and a series of
shorts may happen if the offending bulb is not replaced quickly.
Strings with larger number of lights in series are not as likely to
fail from just one burnt-out bulb, but the overall kife is shortened,
and it is always a good idea to replace bad bulbs to keep the rest
happy.

H. R. (Bob) Hofmann






chris@nospam.com wrote in message news:<815duvo6d2h3ng5f723leg8k14uq1ne2hb@4ax.com>...
On Mon, 22 Dec 2003 04:02:31 GMT, "James Sweet"
jamessweet@hotmail.com> wrote:


sponger09@comcastONOSPAM.net> wrote in message
news:mg5auvkrhiie92b6v8dp4f9qpm9qnhjrj7@4ax.com...
On Sat, 20 Dec 2003 20:33:37 -0600, "Ralph Wade Phillips"
ralphp@techie.com> wrote:

Howdy!

"JohnMB" <usedforpostingonly@hotmail.com> wrote in message
news:2b52ab59.0312201708.29b6fce0@posting.google.com...
Hi, how is it please that a modern Christmas tree bulb can fail to
light, yet not break a series circuit? Thats clever... how is it done
please.

You mean those little ones?

There's a high resistance bleeder across the lamp that allows the
OTHER lamps to keep on running, even if this bulb burns out.

RwP

So why don't they wire them in parallel, to begin with?

Dwight.

Because it's very hard to make efficient low wattage filaments with a
voltage as high as 120v (or 240 even in other parts of the world), it's much
easier to use a string of low voltage bulbs in series. Larger C7 and C9
strings use 120v bulbs in parallel.

It's also cheaper to make safe low voltage sockets.
Click to expand...
 
So, what is the reason they put that thing there? I would prefer when a bulb
blows the current stops flowing so other bulbs do not receive more voltage
and do not blow.

Sam Goldwasser expuso:
There is an "anti-fuse" in there that shorts out
when more than a specific breakdown voltage appears across it. This
will happen when the lamp burns out. Of course, when a lamp burns
out and shorts out, slightly more voltage will be present across all
the other lamps. When enough lamps burn out and short, the entire
string will go up in one spectacular display of fireworks.
Hopefully, there is a properly sized fuse in series with the string!
:)

Examine the lamp that doesn't light. You'll find a bar across the
filament leads. That's the short. When the lamp is alive, it's
insulated from the filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the
string
will go out.

--- sam | Sci.Electronics.Repair FAQ Home Page:
http://www.repairfaq.org/ Repair | Main Table of Contents:
http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:
http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work. To contact me, please use the feedback form on the S.E.R FAQ
Web sites.
Click to expand...
 
The problem then is that you have a dead string and no idea which one is the
culprit, which is the way they used to be 30 years ago. With the
introduction of the "wire" at least you have a chance of finding bad ones
easier.

WT

"Jeroni Paul" <JERONI.PAUL@terra.es> wrote in message
news:bsa5r7$b6fl2$1@ID-215914.news.uni-berlin.de...
So, what is the reason they put that thing there? I would prefer when a
bulb
blows the current stops flowing so other bulbs do not receive more voltage
and do not blow.

Sam Goldwasser expuso:
There is an "anti-fuse" in there that shorts out
when more than a specific breakdown voltage appears across it. This
will happen when the lamp burns out. Of course, when a lamp burns
out and shorts out, slightly more voltage will be present across all
the other lamps. When enough lamps burn out and short, the entire
string will go up in one spectacular display of fireworks.
Hopefully, there is a properly sized fuse in series with the string!
:)

Examine the lamp that doesn't light. You'll find a bar across the
filament leads. That's the short. When the lamp is alive, it's
insulated from the filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the
string
will go out.

--- sam | Sci.Electronics.Repair FAQ Home Page:
http://www.repairfaq.org/ Repair | Main Table of Contents:
http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:
http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info:
http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer
work. To contact me, please use the feedback form on the S.E.R FAQ
Web sites.
Click to expand...
 
"Jeroni Paul" <JERONI.PAUL@terra.es> wrote in message
news:bsa5r7$b6fl2$1@ID-215914.news.uni-berlin.de...
So, what is the reason they put that thing there? I would prefer when a
bulb
blows the current stops flowing so other bulbs do not receive more voltage
and do not blow.
Click to expand...
The old C6 lights were like that, it was horrible, the whole string would go
out when a single bulb failed, you should try chasing down a dead bulb on a
decorated christmas tree and see how easy it is to follow the string and
test all the bulbs. The little fuse is a great invention, when a bulb burns
out you simply replace it, it's not like it'll instantly blow all the rest
of the bulbs, I only had that happen once, and it was a small string that
was on 24/7 unnattended for several days.
 
"Jeroni Paul" <JERONI.PAUL@terra.es> writes:

So, what is the reason they put that thing there? I would prefer when a bulb
blows the current stops flowing so other bulbs do not receive more voltage
and do not blow.
Click to expand...
So you know which lamp burned out. As long as only a couple burn out,
there is no realy problem. And, you would notice and replace them.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

Sam Goldwasser expuso:
There is an "anti-fuse" in there that shorts out
when more than a specific breakdown voltage appears across it. This
will happen when the lamp burns out. Of course, when a lamp burns
out and shorts out, slightly more voltage will be present across all
the other lamps. When enough lamps burn out and short, the entire
string will go up in one spectacular display of fireworks.
Hopefully, there is a properly sized fuse in series with the string!
:)

Examine the lamp that doesn't light. You'll find a bar across the
filament leads. That's the short. When the lamp is alive, it's
insulated from the filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the
string will go out.
Click to expand...
 
In article <bsa6sr$barie$1@id-201804.news.uni-berlin.de>,
"Wayne Tiffany" <wayne.tiffany@asi.com> writes:
The problem then is that you have a dead string and no idea which one is the
culprit, which is the way they used to be 30 years ago. With the
introduction of the "wire" at least you have a chance of finding bad ones
easier.
Click to expand...
Of course, that's assuming that one is using miniature light bulbs.
Thirty years ago, many people still used the larger light bulbs.
I've never used miniature light bulbs on Christmas trees, always the
colored bulbs that are about an inch and a half high, from base to tip
and about 3/4" around, wired in parallel... grew up with those, and
still use some of the same sets of lights... the older ones were much
better made and easier to string on the tree, since the wires weren't
as stiff. The little lights were only used in the windows, which they
could be Scotch Taped to... and no blinking lights! (except for the
red bells that made a tinkling sound when they blinked on and off) It
isn't that often that the little miniature bulbs burn out, but when
they do, it only takes a few minutes to use a battery-operated bulb
tester to check all of the bulbs on a string.

--
Copyright (C) 2003 R. D. Davis The difference between humans & other animals:
All Rights Reserved an unnatural belief that we're above Nature &
rdd@rddavis.org 410-744-4900 her other creatures, using dogma to justify such
http://www.rddavis.org beliefs and to justify much human cruelty.
 
On 23 Dec 2003 19:15:19 -0500, Bob Horvath wrote:


My son-in-law just bought some GE Constant on mini lite strings that
stay lit even if you pull bulbs out, He said that they advise not to
use them if there are only 4 or 5 bulbs left, but it sure is nice to
see them stay lit with bulbs missing.
Bob
"Jeroni Paul" <JERONI.PAUL@terra.es> writes:

So, what is the reason they put that thing there? I would prefer when a bulb
blows the current stops flowing so other bulbs do not receive more voltage
and do not blow.

So you know which lamp burned out. As long as only a couple burn out,
there is no realy problem. And, you would notice and replace them.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

Sam Goldwasser expuso:
There is an "anti-fuse" in there that shorts out
when more than a specific breakdown voltage appears across it. This
will happen when the lamp burns out. Of course, when a lamp burns
out and shorts out, slightly more voltage will be present across all
the other lamps. When enough lamps burn out and short, the entire
string will go up in one spectacular display of fireworks.
Hopefully, there is a properly sized fuse in series with the string!
:)

Examine the lamp that doesn't light. You'll find a bar across the
filament leads. That's the short. When the lamp is alive, it's
insulated from the filament leads by a very thin layer of something.

The clincher is that if you pull that lamp out of the string, the
string will go out.
Click to expand...
 
Bob Horvath <bhorvath13@comcast.net> writes:

My son-in-law just bought some GE Constant on mini lite strings that
stay lit even if you pull bulbs out, He said that they advise not to
use them if there are only 4 or 5 bulbs left, but it sure is nice to
see them stay lit with bulbs missing.
Click to expand...
So you have to find an excuse to go over to his place and see what's
in there. My first guess would be a some diodes and resistors that
will bypass current if the voltage is greater than the normal 2 V or
whatever. But could be much more sophisticated.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.
 
Howdy!

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qvozbnk.fsf@saul.cis.upenn.edu...

So you have to find an excuse to go over to his place and see what's
in there. My first guess would be a some diodes and resistors that
will bypass current if the voltage is greater than the normal 2 V or
whatever. But could be much more sophisticated.
Click to expand...
Simpler than that.

The bulb has a blade on the bottom, and it pushes between two metal
blades when you insert the bulb. When the bulb is removed,the two metal
blades touch.

So - either the bulb is inserted, and provides continuity, or the
blades touch, and provide continuity.

RwP
 
On Thu, 25 Dec 2003 20:30:37 -0600, Bob Horvath wrote:


Thanks for the info.

Howdy!

"Sam Goldwasser" <sam@saul.cis.upenn.edu> wrote in message
news:6w4qvozbnk.fsf@saul.cis.upenn.edu...


So you have to find an excuse to go over to his place and see what's
in there. My first guess would be a some diodes and resistors that
will bypass current if the voltage is greater than the normal 2 V or
whatever. But could be much more sophisticated.

Simpler than that.

The bulb has a blade on the bottom, and it pushes between two metal
blades when you insert the bulb. When the bulb is removed,the two metal
blades touch.

So - either the bulb is inserted, and provides continuity, or the
blades touch, and provide continuity.

RwP
Click to expand...
 
Wow. That would make a really spectacular display if all the lamps
were removed then the power was applied! :)


"Ralph Wade Phillips" <ralphp@techie.com> wrote:
Simpler than that.

The bulb has a blade on the bottom, and it pushes between two metal
blades when you insert the bulb. When the bulb is removed,the two metal
blades touch.

So - either the bulb is inserted, and provides continuity, or the
blades touch, and provide continuity.

RwP
Click to expand...
 
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