G
George Herold
Guest
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
George H.
How da do dat? OK I'm feeling lazy and not searc...
George H.
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R
Rich Grise
Guest
George Herold wrote:
Cheers!
Rich
filament melts/vaporizes.Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Springy filament supports that short to another contact when the
Cheers!
Rich
G
George Herold
Guest
On Jan 5, 9:39 pm, Rich Grise <ri...@example.net.invalid> wrote:
out the support makes contact on the other side?
George H.
Oh, the filament holds the (springie) support back, and when it burnsGeorge Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Springy filament supports that short to another contact when the
filament melts/vaporizes.
Cheers!
Rich
out the support makes contact on the other side?
George H.
R
Rich Grise
Guest
George Herold wrote:
Good Luck!
Rich
break the envelope, and look and see?On Jan 5, 9:39 pm, Rich Grise <ri...@example.net.invalid> wrote:
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Springy filament supports that short to another contact when the
filament melts/vaporizes.
Oh, the filament holds the (springie) support back, and when it burns
out the support makes contact on the other side?
That's the way I understand it, yes. Maybe sacrifice one, carefully
Good Luck!
Rich
S
Sjouke Burry
Guest
George Herold wrote:
High voltage kills something in the foot of the broken light,
causing a short.
Until the higher voltages on the rest kill the whole chain....Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
George H.
Thats to keep the others burning.
High voltage kills something in the foot of the broken light,
causing a short.
K
krw@att.bizzzzzzzzzzzz
Guest
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
are series strung and recent ones have the short-in-the-base thing.
wrote:
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis thatIn <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
are series strung and recent ones have the short-in-the-base thing.
D
Don Klipstein
Guest
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
--
- Don Klipstein (don@misty.com)
George Herold wrote:
Many incandescents made for use in series strings are designed toXmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
--
- Don Klipstein (don@misty.com)
J
Jasen Betts
Guest
On 2011-01-06, George Herold <ggherold@gmail.com> wrote:
wire wrapped around the filament supports, I guess it has a coating
that will burn through when it's hit by the fault voltage and become
conductive.
--
ââ 100% natural
looking through the glass envelope I see what appears to be a bunch ofXmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
George H.
wire wrapped around the filament supports, I guess it has a coating
that will burn through when it's hit by the fault voltage and become
conductive.
--
ââ 100% natural
M
Michael A. Terrell
Guest
"krw@att.bizzzzzzzzzzzz" wrote:
A pair of anti-parallel Zeners would be better.
--
What are you looking for, all the way down here?
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
--
What are you looking for, all the way down here?
G
George Herold
Guest
On Jan 6, 6:29Â am, Jasen Betts <ja...@xnet.co.nz> wrote:
http://www.ciphersbyritter.com/RADELECT/LITES/XMSLITES.HTM
Thanks.
George H.
I found a picture here,On 2011-01-06, George Herold <ggher...@gmail.com> wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? Â OK I'm feeling lazy and not searc...
George H.
looking through the glass envelope I see what appears to be a bunch of
wire wrapped around the filament supports, I guess it has a coating
that will burn through when it's hit by the fault voltage and become
conductive.
--
ââ 100% natural
http://www.ciphersbyritter.com/RADELECT/LITES/XMSLITES.HTM
Thanks.
George H.
K
krw@att.bizzzzzzzzzzzz
Guest
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:
<mike.terrell@earthlink.net> wrote:
1V Zeners are really lousy."krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
B
Bob Masta
Guest
On Thu, 06 Jan 2011 18:22:27 -0600, "krw@att.bizzzzzzzzzzzz"
<krw@att.bizzzzzzzzzzzz> wrote:
knee. Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g>
Best regards,
Bob Masta
DAQARTA v6.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!
<krw@att.bizzzzzzzzzzzz> wrote:
On the other hand, forward-biased LEDs have a pretty sharpOn Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
knee. Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g>
Best regards,
Bob Masta
DAQARTA v6.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!
M
Michael A. Terrell
Guest
"krw@att.bizzzzzzzzzzzz" wrote:
They don't have to be that low. If they were, they would all be so
soft that the leakage current would be higher than the lamp current.
Anyway, I don't recall a 120 lamp string with 1 V lbulbs. The 100 lamp
I've seen had two strings of 50, with a three wire cord. That means the
bulbs are 2.4 volts, so a working lamp has 1.2 *1.414 or 3.3936 volts
peak across a lit bulb. Five volt Zeners would be fine, ssince you
don't want them to conduct, except under failure mode.
Some people who restore old series string tube radios use a pair of 9
volt across the pilot lamps which are powered off a tap in the filament
in the 35 V rectifier. You can lose the tube, when the pilot lamp burns
out but the pair of diodes will protect it. It was my idea, and I had
to argue with them for a while before it sank in. They kept insisting
that you needed 6.3 volt Zeners acrross a 6.3 volt pilot lamp. Of
course, these are the same people who insisted that putting a diode in
series with a string of filaments cut the effective voltage in half.
--
What are you looking for, all the way down here?
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
They don't have to be that low. If they were, they would all be so
soft that the leakage current would be higher than the lamp current.
Anyway, I don't recall a 120 lamp string with 1 V lbulbs. The 100 lamp
I've seen had two strings of 50, with a three wire cord. That means the
bulbs are 2.4 volts, so a working lamp has 1.2 *1.414 or 3.3936 volts
peak across a lit bulb. Five volt Zeners would be fine, ssince you
don't want them to conduct, except under failure mode.
Some people who restore old series string tube radios use a pair of 9
volt across the pilot lamps which are powered off a tap in the filament
in the 35 V rectifier. You can lose the tube, when the pilot lamp burns
out but the pair of diodes will protect it. It was my idea, and I had
to argue with them for a while before it sank in. They kept insisting
that you needed 6.3 volt Zeners acrross a 6.3 volt pilot lamp. Of
course, these are the same people who insisted that putting a diode in
series with a string of filaments cut the effective voltage in half.
--
What are you looking for, all the way down here?
M
Michael A. Terrell
Guest
Bob Masta wrote:
Want to try that again? After too many lamps fail, the forward
voltage would be too hight to light your LEDs.
--
What are you looking for, all the way down here?
On Thu, 06 Jan 2011 18:22:27 -0600, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
On the other hand, forward-biased LEDs have a pretty sharp
knee. Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g
Want to try that again? After too many lamps fail, the forward
voltage would be too hight to light your LEDs.
--
What are you looking for, all the way down here?
K
krw@att.bizzzzzzzzzzzz
Guest
On Fri, 07 Jan 2011 13:36:40 GMT, N0Spam@daqarta.com (Bob Masta) wrote:
Nonsense.On Thu, 06 Jan 2011 18:22:27 -0600, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
On the other hand, forward-biased LEDs have a pretty sharp
knee.
Perhaps you're wasting money on the incandescent lamp?Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g
K
krw@att.bizzzzzzzzzzzz
Guest
On Fri, 07 Jan 2011 09:29:37 -0500, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:
<mike.terrell@earthlink.net> wrote:
Power dissipation?"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
They don't have to be that low. If they were, they would all be so
soft that the leakage current would be higher than the lamp current.
Anyway, I don't recall a 120 lamp string with 1 V lbulbs. The 100 lamp
I've seen had two strings of 50, with a three wire cord. That means the
bulbs are 2.4 volts, so a working lamp has 1.2 *1.414 or 3.3936 volts
peak across a lit bulb. Five volt Zeners would be fine, ssince you
don't want them to conduct, except under failure mode.
Some people who restore old series string tube radios use a pair of 9
volt across the pilot lamps which are powered off a tap in the filament
in the 35 V rectifier. You can lose the tube, when the pilot lamp burns
out but the pair of diodes will protect it. It was my idea, and I had
to argue with them for a while before it sank in. They kept insisting
that you needed 6.3 volt Zeners acrross a 6.3 volt pilot lamp. Of
course, these are the same people who insisted that putting a diode in
series with a string of filaments cut the effective voltage in half.
M
Michael A. Terrell
Guest
"krw@att.bizzzzzzzzzzzz" wrote:
Geeze! It's kind of pointless now, but before LED strings were
availible it would have been worth the time & effort to manufacture
series strings with the diodes to make it easy to find the bad lamps.
The entire string is just a few watts. Did you know that there are plug
in LED replacements for the mini incandescent lamps?
--
What are you looking for, all the way down here?
On Fri, 07 Jan 2011 09:29:37 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
They don't have to be that low. If they were, they would all be so
soft that the leakage current would be higher than the lamp current.
Anyway, I don't recall a 120 lamp string with 1 V lbulbs. The 100 lamp
I've seen had two strings of 50, with a three wire cord. That means the
bulbs are 2.4 volts, so a working lamp has 1.2 *1.414 or 3.3936 volts
peak across a lit bulb. Five volt Zeners would be fine, since you
don't want them to conduct, except under failure mode.
Power dissipation?
Geeze! It's kind of pointless now, but before LED strings were
availible it would have been worth the time & effort to manufacture
series strings with the diodes to make it easy to find the bad lamps.
The entire string is just a few watts. Did you know that there are plug
in LED replacements for the mini incandescent lamps?
--
What are you looking for, all the way down here?
M
Michael A. Terrell
Guest
Bob Masta wrote:
It would have been funny if it was possible. The idea for the zeners
was something from long before they sold LED strings.
--
What are you looking for, all the way down here?
On Fri, 07 Jan 2011 09:31:03 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
Bob Masta wrote:
On Thu, 06 Jan 2011 18:22:27 -0600, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
On the other hand, forward-biased LEDs have a pretty sharp
knee. Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g
Want to try that again? After too many lamps fail, the forward
voltage would be too hight to light your LEDs.
Hey, it was a joke, after all! The idea was that the
incandescents are the current limiting resistors for the
LEDs, so if all the incandescents failed there would be no
current limiting. Assuming red LEDs at 1.4V each, that
would let the magic smoke out. But of course, why would
anyone bother with incandescents if they had LEDs?
It would have been funny if it was possible. The idea for the zeners
was something from long before they sold LED strings.
--
What are you looking for, all the way down here?
B
Bob Masta
Guest
On Fri, 07 Jan 2011 09:31:03 -0500, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:
incandescents are the current limiting resistors for the
LEDs, so if all the incandescents failed there would be no
current limiting. Assuming red LEDs at 1.4V each, that
would let the magic smoke out. But of course, why would
anyone bother with incandescents if they had LEDs?
Best regards,
Bob Masta
DAQARTA v6.00
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Sound Level Meter
Frequency Counter, FREE Signal Generator
Pitch Track, Pitch-to-MIDI
Science with your sound card!
<mike.terrell@earthlink.net> wrote:
Hey, it was a joke, after all! The idea was that theBob Masta wrote:
On Thu, 06 Jan 2011 18:22:27 -0600, "krw@att.bizzzzzzzzzzzz"
krw@att.bizzzzzzzzzzzz> wrote:
On Thu, 06 Jan 2011 10:49:46 -0500, "Michael A. Terrell"
mike.terrell@earthlink.net> wrote:
"krw@att.bizzzzzzzzzzzz" wrote:
On Thu, 6 Jan 2011 05:13:14 +0000 (UTC), don@manx.misty.com (Don Klipstein)
wrote:
In <9e4702ff-8bf3-4692-bcf8-4b847cdaae26@r19g2000prm.googlegroups.com>,
George Herold wrote:
Xmas tree incandesent's die as dead shorts.
How da do dat? OK I'm feeling lazy and not searc...
Many incandescents made for use in series strings are designed to
become shorts upon being presented with full line voltage as a result of
failing open. The explanation that I usually hear is add-on parts that
short upon receiving full line voltage.
On the other hand, 120V incandescents used for Christmas (generally C7
and C9) fail open and stay open. If they become shorts instead, then
burnouts would pop breakers or pop something.
C7s and C9s are usually parallel strung (w/ 120V bulbs). It's the minis that
are series strung and recent ones have the short-in-the-base thing.
A pair of anti-parallel Zeners would be better.
1V Zeners are really lousy.
On the other hand, forward-biased LEDs have a pretty sharp
knee. Hey, then after the incandescent blew out, the LEDs
would carry on forever! Or until enough of the other
incandescents blew to prevent current limiting... <g
Want to try that again? After too many lamps fail, the forward
voltage would be too hight to light your LEDs.
incandescents are the current limiting resistors for the
LEDs, so if all the incandescents failed there would be no
current limiting. Assuming red LEDs at 1.4V each, that
would let the magic smoke out. But of course, why would
anyone bother with incandescents if they had LEDs?
Best regards,
Bob Masta
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