Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default LED Series Christmas Lights

I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. There are
also a couple of lumps in the series lines. They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. Has anyone
done any experimenting like this?
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Default LED Series Christmas Lights


" wrote:

I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. There are
also a couple of lumps in the series lines. They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. Has anyone
done any experimenting like this?



Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose 35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.


--
You can't have a sense of humor, if you have no sense.
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Default LED Series Christmas Lights

On Dec 27, 2:58*pm, Cydrome Leader wrote:
wrote:
I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. *There are
also a couple of lumps in the series lines. *They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. * My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. *I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. *Has anyone
done any experimenting like this?


my guess is the string won't even light up with 70 LEDs in series. Messing
with that resistor will probably make the thing an even bigger fire hazard
than it is now. If you really want a long string of lights, just add an
extra wire the length of the first one to power the second and have the
use a common return line. Old zip lamp cord or speaker wire works nice for
stuff like this.


The separate sets have an outlet at the far end, so easy to put
together. My posting was just curiosity.

Back in 1944, when I was only 8 years old, my grandmother took me to
Macy's in New York City to buy me a Christmas present. She was
horrifed that the only present I wanted was a string of Christmas
lights so I could play with the bulbs and wires. First inkling I was
destined to become an electgrical engineer.

Fast forward to 1957, when I graduated from college with a EE degree
and got a job at Bell Laboratories. I had a dream job designing
switching system interconnect circuits, but also enjoyed playing with
Christmas lights.

Really fast forward to 2011, I still enjoy playing with Christmas
lights.
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Default LED Series Christmas Lights

On Dec 27, 12:54*am, "Michael A. Terrell"
wrote:
" wrote:

I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. *There are
also a couple of lumps in the series lines. *They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. * My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. *I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. *Has anyone
done any experimenting like this?


* *Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose *35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. *If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.

--
You can't have a sense of humor, if you have no sense.


Good point about surge limiting, altho I am not sure if LEDs are any
more susceptible than tungsten filament lamps.


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On Tue, 27 Dec 2011 17:49:09 -0800 (PST), "
wrote:

Back in 1944, when I was only 8 years old, my grandmother took me to
Macy's in New York City to buy me a Christmas present. She was
horrifed that the only present I wanted was a string of Christmas
lights so I could play with the bulbs and wires. First inkling I was
destined to become an electgrical engineer.


My first indication of the same affliction was shoving my fingers into
the wall outlet. I assume the resultant shock didn't cause any
lasting harm, but I'm not sure. My logic was that anything that
powerful was worth learning. It's been downhill since then.

Fast forward to 1957, when I graduated from college with a EE degree
and got a job at Bell Laboratories. I had a dream job designing
switching system interconnect circuits, but also enjoyed playing with
Christmas lights.


When I graduated from college in approximately 1971, aerospace and the
space program had just collapsed. I ended up with a job installing
radios in cement mixers. No flashing lights or electrocution devices
at the time.

Really fast forward to 2011, I still enjoy playing with Christmas
lights.


It's almost 2012 and I'm going broke fixing electronics and giving
away free advice on Usenet. So, I'm slowly switching back to fixing
sewing machines. (I was my fathers ace mechanic when he owned a
factory in the L.A. garment district). No flashing lights, but plenty
opportunity to do damage.

I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
#
http://www.LearnByDestroying.com AE6KS
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" wrote:

On Dec 27, 12:54 am, "Michael A. Terrell"
wrote:
" wrote:

I recently was given two strings of LED blue/white Christmas lights.
The bulbes are in series, with 35 lights in each string. There are
also a couple of lumps in the series lines. They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. Has anyone
done any experimenting like this?


Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose 35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.


Good point about surge limiting, altho I am not sure if LEDs are any
more susceptible than tungsten filament lamps.



Tungsten has a time constant, and the resistance goes up as the
voltage increases. LEDs are current operated at a lot more constant
voltage. A few volt rise in the power line rasies the current flow.
Harmonics and spikes on the power line will cause higher peak current
flow in the LEDs. It would be like operating a Zener very close to it's
knee voltage with only a very low resistance to limit the current.


--
You can't have a sense of humor, if you have no sense.
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Default LED Series Christmas Lights

On Dec 27, 10:10*pm, "Michael A. Terrell"
wrote:
" wrote:

On Dec 27, 12:54 am, "Michael A. Terrell"
wrote:
" wrote:


I recently was given two strings of LED blue/white Christmas lights..
The bulbes are in series, with 35 lights in each string. *There are
also a couple of lumps in the series lines. *They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. * My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. *I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. *Has anyone
done any experimenting like this?


* *Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose *35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. *If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.


Good point about surge limiting, altho I am not sure if LEDs are any
more susceptible than tungsten filament lamps.


* *Tungsten has a time constant, and the resistance goes up as the
voltage increases. *LEDs are current operated at a lot more constant
voltage. *A few volt rise in the power line rasies the current flow.
Harmonics and spikes on the power line will cause higher peak current
flow in the LEDs. It would be like operating a Zener very close to it's
knee voltage with only a very low resistance to limit the current.


The variation in atom size in III-V semiconductors creates more
defects than a homogeneous semiconductor like silicon would have,
because of the strained lattice. High currents will propagate those
defects, creating areas where the steady-state current will bypass the
p-n junctions (so-called dark current, because it doesn't produce
light). So the useful life of the LED string would be unnecessarily
reduced.
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"Jeff Liebermann" wrote in message
...

I do like Christmas lights, but they only last until the squirrels
are done chewing on the wires.


"Done", as in "thoroughly cooked"?

It would break your mother's heart if she knew you liked Christmas lights.


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Default LED Series Christmas Lights

On Dec 28, 5:49*am, "William Sommerwerck"
wrote:
"Jeff Liebermann" wrote in message

...

I do like Christmas lights, but they only last until the squirrels
are done chewing on the wires.


"Done", as in "thoroughly cooked"?

It would break your mother's heart if she knew you liked Christmas lights..


When I was 13 I reasoned that if you got a whole bunch of extension
cords and plugged them into various different outlets in the house,
then wired them all in series you could achieve infinite
possibilities. That was only topped by the 120.0 V to 6.0 volt step
down transformer I tried to wind on the metal frame of my bed. The
schematic showed 8 turns on the primary and 2 on the secondary.
Couldn't figure out why I lit up he room.....Lenny


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On Wed, 28 Dec 2011 02:49:44 -0800, "William Sommerwerck"
wrote:

"Jeff Liebermann" wrote in message
.. .

I do like Christmas lights, but they only last until the squirrels
are done chewing on the wires.


"Done", as in "thoroughly cooked"?


I use solar powered LED lights. Besides using less power, it's more
ecologically correct by not electrocuting the squirrels. I leave the
lights in place all year to light up the stairs and balcony, leaving
plenty of opportunities for the squirrels to ruin my day. One string
has perhaps 10 splices. The squirrels are cute, but they're rather
destructive.

It would break your mother's heart if she knew you liked Christmas lights.


Nope. Hannukah is the Festival of Lights. The story of Esther
specifies using oil lamps, which is proscribed in the local fire code.
So, we use electric lights. As long as the lights looked something
like a menorah, my parents were satisfied. However, they drew the
line with the Hannukah bush. I wanted to also celebrate Christmas,
but when they told me that Hannukah was 8 days, and that I was suppose
to get one present per day, I decided I could live without Christmas.
Unfortunately, the added presents were fairly tacky:
http://en.wikipedia.org/wiki/Hanukkah_gelt
Lesson learned: Next time, get it in writing.

Hannukah also created another area of contention over playing the
dreidel.
http://en.wikipedia.org/wiki/Dreidel
Basically, it was gambling, which my parents tended to discourage but
tolerated because it taught useful skills (math, statistics,
probability, bookkeeping, loans, etc). Us kids were soon bored with
the dreidel, and switched to playing craps with dice. It was many
years before I could understand why the dreidel was acceptable, but
the dice were not.

At some point, when I was about 15, I morphed into a very junior
Beatnick.
http://en.wikipedia.org/wiki/Beatnick
Glorified poverty and a minimalist lifestyle meant that I was required
to discard all the trappings of affluence, reject all modern
conveniences, drop out of society, avoid clean clothes, and read
poetry, thus somehow demonstrating that I was a non-conformist. My
parents interpreted that as a rebellion, which they celebrated by
cutting off my allowance, demanding that I wash the dishes, and
refusing to supply the ritualistic gifts on the usual occassions. This
made life intolerable, so I ran away from home. I eventually
returned, somewhat wiser, just in time for Hannukah. After receiving
the requisit lecture, I was welcomed with a peace offering gift, which
I gratefully accepted, thus ending my life as a non-conformist. The
lights of Hannukah will always remind me of my first major screwup.

Happy Holidaze.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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Default LED Series Christmas Lights

Jeff Liebermann wrote:
to get one present per day, I decided I could live without Christmas.
Unfortunately, the added presents were fairly tacky:
http://en.wikipedia.org/wiki/Hanukkah_gelt


My son asked me, as a joke, if I could buy him a 5 trillion dollar Zibabwean
bill from eBay. I thought he was serious, so in the grand tradition of
Chanuka Gelt, he got 5 trillion dollars yesterday. :-)

It's made quite a splash in the humor section of redit.

Geoff.


--
Geoffrey S. Mendelson, N3OWJ/4X1GM
My high blood pressure medicine reduces my midichlorian count. :-(


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Jeff Liebermann wrote:
I do like Christmas lights, but
they only last until the squirrels are done chewing on the wires.

I see rodent-related threads hereabouts from time to time.
The solution has been know for eons.
That is the proper seeds in birdfeeders
and the proper vegetable extract applied to other things:
http://google.com/search?q=Hobanero-video
Those little dudes will leave skid marks getting away.
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On Wed, 28 Dec 2011 17:29:03 +0000 (UTC), "Geoffrey S. Mendelson"
wrote:

Jeff Liebermann wrote:
to get one present per day, I decided I could live without Christmas.
Unfortunately, the added presents were fairly tacky:
http://en.wikipedia.org/wiki/Hanukkah_gelt


My son asked me, as a joke, if I could buy him a 5 trillion dollar Zibabwean
bill from eBay. I thought he was serious, so in the grand tradition of
Chanuka Gelt, he got 5 trillion dollars yesterday. :-)
It's made quite a splash in the humor section of redit.


A what? Digging....
http://www.ebay.com/itm/270863837896
http://www.ebay.com/itm/250943869930
Plenty of others. Great idea for Hannukah. I wish you had mentioned
it a few weeks ago so I could have used it on the spoiled brats.

My father used Hannukah gelt to introduce me to how money works. I
think I was 6 years old at the time. He gave me an old silver dollar,
and informed me that it was worth more than a dollar. Huh? This was
new to me. Explanations were useless, but I kept the dollar well
hidden, looking occasionally to see if it would grow. By about 10
years old, I was the only kid in skool with a (co-signed) bank
account. I was buying stock when I was 16. The lessons were
invaluable.

There are lots of lessons that should be applied or demonstrated
early. That includes how to repair things. My father was always
fixing things around the house or delivered by friends. Repaired
presents were common. I just assumed that he enjoyed fixing things.
Later, I found out that he only repaired things because we were
sufficiently broke to not be able to afford new items. However, it
was too late. By then, I was fixing (well, attempting to fix) things
and was hooked.

These days, repair work has changed. In the bad old days, it was
assumed that most items worth repairing were of decent quality. These
days, I can't just repair things. I have to re-engineer the design
and try to improve on what I consider to be crappy design and shoddy
construction. In the past, products were usually designed to be
maintained. These days, they're designed to be non-repairable.
Actually, it's not repair as much as it is remanufacture. In some
product areas, it's impossible to buy quality at any price.

Ok. That's my holiday rant.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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On Wed, 28 Dec 2011 10:31:03 -0800 (PST), JeffM
wrote:

Jeff Liebermann wrote:
I do like Christmas lights, but
they only last until the squirrels are done chewing on the wires.

I see rodent-related threads hereabouts from time to time.
The solution has been know for eons.
That is the proper seeds in birdfeeders
and the proper vegetable extract applied to other things:
http://google.com/search?q=Hobanero-video
Those little dudes will leave skid marks getting away.


http://en.wikipedia.org/wiki/Habanero_chili
Interesting idea, but I don't think it will work in the deep dark
forest. Chili peppers require a warm climate, dry acidic soil, and
plenty of sun. Where I live, only the acidic soil is available. Also,
I don't think it will be practical installing chili planters along the
hand rails and roof edge, where the Christmas lamps live.



--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558


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On Dec 29, 8:02*am, Andrew Rossmann
wrote:
In article 8b7174c5-7170-4ec6-9871-c33915515084
@f1g2000yqi.googlegroups.com, says...

Really fast forward to 2011, I still enjoy playing with Christmas
lights.


As long as you can get them back into a nice string instead of a bundled
ball!

--
If there is a no_junk in my address, please REMOVE it before replying!
All junk mail senders will be prosecuted to the fullest extent of the
law!!http://home.comcast.net/~andyross


I use corrogated (sp?) cardboard , about 12" tall and 5" wide, with an
hourglass waist so the 5" is only 3" wide and wrap them around that.
I make sure to roll them up, not twirl them up, so that they don't
rotate the remaining string as I wind them on. Works great getting
them back off except on those strings that have little ears on the
sockets for the anchor-style bulbs, or those mesh style sockets where
there are two ears used to make the mesh netting effect. Oh well, if
that's the worst thing in life, I have it pretty easy. There are some
advantagers to getting old and being retired so I have time to play
with these things.
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On Dec 27, 7:49*pm, Jeff Liebermann wrote:

It's almost 2012 and I'm going broke fixing electronics and giving
away free advice on Usenet. So, I'm slowly switching back to fixing
sewing machines. (I was my fathers ace mechanic when he owned a
factory in the L.A. garment district). No flashing lights, but plenty
opportunity to do damage.


Where are teh sweatshops?

I remember when South of Market was the garment district of San
Francisco, but I don't think Esprit and Gunne Saxe, etc., are still
sewn there.

Much to my surprise, the venerable Union Special Machine Co is still
in existence -- although as a division of Juki -- making mostly
specialty machines for such applications as bags and Astroturf.
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On Thu, 29 Dec 2011 19:04:33 -0800 (PST), spamtrap1888
wrote:

On Dec 27, 7:49*pm, Jeff Liebermann wrote:

It's almost 2012 and I'm going broke fixing electronics and giving
away free advice on Usenet. So, I'm slowly switching back to fixing
sewing machines. (I was my fathers ace mechanic when he owned a
factory in the L.A. garment district). No flashing lights, but plenty
opportunity to do damage.


Where are teh sweatshops?


Alive and well in China and Vietnam.
https://www.google.com/search?q=china+sweatshops&tbm=isch
We sold the biz shortly after my father had a stroke in 1986. At the
time, the downtown area of Smog Angeles was in the process of morphing
into a disaster area. Reputable businesses and stores were moving
out, to be replaced by importers, discounters, and empty factories.
http://www.thesanteealley.com
Very little of what's being sold was made locally.

Many garment manufacturers were purchased and had the entire factory
shipped overseas. Most of the garment production initially went to
Korea, which was also the main source of synthetic material. It then
shifted to Viet Nam where there are still large factories. Viet Nam
couldn't handle the huge growth in low cost clothes, so much of the
business went to China. Some also went to Mexican maquiladoras, but
nothing compared to the volume in China.

New York isn't doing any better than Smog Angeles:
http://savethegarmentcenter.org

I remember when South of Market was the garment district of San
Francisco, but I don't think Esprit and Gunne Saxe, etc., are still
sewn there.

Much to my surprise, the venerable Union Special Machine Co is still
in existence -- although as a division of Juki -- making mostly
specialty machines for such applications as bags and Astroturf.


In the garment biz, most items require a specialty attachment in order
to be efficient. You start with a basic machine, and then add
attachments, fixtures, and automation, all of which are highly
customized. The average lifetime of a style or pattern does not lend
itself to dedicated machines.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
#
http://www.LearnByDestroying.com AE6KS
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On Dec 29, 8:01*pm, Jeff Liebermann wrote:
On Thu, 29 Dec 2011 19:04:33 -0800 (PST), spamtrap1888

wrote:
On Dec 27, 7:49*pm, Jeff Liebermann wrote:


It's almost 2012 and I'm going broke fixing electronics and giving
away free advice on Usenet. *So, I'm slowly switching back to fixing
sewing machines. *(I was my fathers ace mechanic when he owned a
factory in the L.A. garment district). *No flashing lights, but plenty
opportunity to do damage.

Where are teh sweatshops?


Alive and well in China and Vietnam.
https://www.google.com/search?q=china+sweatshops&tbm=isch
We sold the biz shortly after my father had a stroke in 1986. *At the
time, the downtown area of Smog Angeles was in the process of morphing
into a disaster area. *Reputable businesses and stores were moving
out, to be replaced by importers, discounters, and empty factories.
http://www.thesanteealley.com
Very little of what's being sold was made locally.

Many garment manufacturers were purchased and had the entire factory
shipped overseas. *Most of the garment production initially went to
Korea, which was also the main source of synthetic material. *It then
shifted to Viet Nam where there are still large factories. *Viet Nam
couldn't handle the huge growth in low cost clothes, so much of the
business went to China. *Some also went to Mexican maquiladoras, but
nothing compared to the volume in China.


So, were you just joking, or are you planning to move to China?


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klem kedidelhopper writes:

On Dec 28, 5:49=A0am, "William Sommerwerck"
wrote:
"Jeff Liebermann" wrote in message

...

I do like Christmas lights, but they only last until the squirrels
are done chewing on the wires.


"Done", as in "thoroughly cooked"?

It would break your mother's heart if she knew you liked Christmas lights=

.


When I was 13 I reasoned that if you got a whole bunch of extension
cords and plugged them into various different outlets in the house,
then wired them all in series you could achieve infinite
possibilities. That was only topped by the 120.0 V to 6.0 volt step
down transformer I tried to wind on the metal frame of my bed. The
schematic showed 8 turns on the primary and 2 on the secondary.
Couldn't figure out why I lit up he room.....Lenny


It's astonishing that we survived until we were able to misunderstand
on a more sophisticated level.

Not as long ago as I would like it to be, I reasoned that since the
magnetron in a 1 megawatt (peak) early-warning radar presented an
impedance of about 500 ohms to the driving circuitry, a 1 kilowatt
microwave oven would use voltages of about 700 volts.
The meter I'd borrowed from a friend to look at his microwave sparked
internally (he claimed there was a blue glow, but he'd seen too many
mad scientist movies).

I now know better, having better access to information!

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost
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Jeff Liebermann writes:

These days, repair work has changed. In the bad old days, it was
assumed that most items worth repairing were of decent quality. These
days, I can't just repair things. I have to re-engineer the design
and try to improve on what I consider to be crappy design and shoddy
construction. In the past, products were usually designed to be
maintained. These days, they're designed to be non-repairable.


Or at least that's what they specifically claim, in some cases.

When my electric toothbrush's battery refused to hold a charge, I
looked at the insane price of replacements and took the old one apart.

It had an O ring which sealed against water ingress, so reusable with
some cleaning, and had a tabbed AA size NiCd which showed normal
voltage until loaded by the motor so obviously dead.

The battery turned out to be suspiciously light. Probably the deluxe
model had a normal AA while my economy model was really a 1/3 AA
internally.

Tinning an NiMH replacement to allow soldering on the tags turned out
to be far easier than I expected; I shouldn't have dabbed on zinc chloride
flux with a cotton swab because this resulted in tinning of the whole
base, thus heating the battery unnecessarily.
A dab from the end of a cocktail stick would have been better (and yes,
I know it's corrosive but supposedly quick tinning is important to
avoid battery damage).

Actually, it's not repair as much as it is remanufacture.


Don't know how long the repair will last, and recharging may take a
long time, but the motor seems to have a bit more power and the first
charge has given many more days of use.

In some
product areas, it's impossible to buy quality at any price.


Or there's little correlation between quality and price.
The bean counters usually get the blame.

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost
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Jeff Liebermann wrote:
I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


In NYC in the 70's squirrels were very rare in the winter, but the lights
lasted a day or two, until the neighbors had stolen half the bulbs.


--

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On Dec 30, 6:13*pm, "Tom Del Rosso" wrote:
Jeff Liebermann wrote:
I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


In NYC in the 70's squirrels were very rare in the winter, but the lights
lasted a day or two, until the neighbors had stolen half the bulbs.

--

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zero, and remove the last word.


There are no squirrels in NYC. The roaches ate them all. Lenny
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On Dec 30, 10:04*pm, klem kedidelhopper
wrote:
On Dec 30, 6:13*pm, "Tom Del Rosso" wrote:

Jeff Liebermann wrote:
I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


In NYC in the 70's squirrels were very rare in the winter, but the lights
lasted a day or two, until the neighbors had stolen half the bulbs.


--


Reply in group, but if emailing add one more
zero, and remove the last word.


There are no squirrels in NYC. The roaches ate them all. Lenny


Naw, the rats eat the squirrels, the roaches eat the rats.


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On Dec 30, 11:45*pm, " wrote:
On Dec 30, 10:04*pm, klem kedidelhopper
wrote:

On Dec 30, 6:13*pm, "Tom Del Rosso" wrote:


Jeff Liebermann wrote:
I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


In NYC in the 70's squirrels were very rare in the winter, but the lights
lasted a day or two, until the neighbors had stolen half the bulbs.


--


Reply in group, but if emailing add one more
zero, and remove the last word.


There are no squirrels in NYC. The roaches ate them all. Lenny


Naw, the rats eat the squirrels, the roaches eat the rats.


Either way it's inevitable who wins in the end.....Lenny
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On Dec 28, 1:10*am, "Michael A. Terrell"
wrote:
" wrote:

On Dec 27, 12:54 am, "Michael A. Terrell"
wrote:
" wrote:


I recently was given two strings of LED blue/white Christmas lights..
The bulbes are in series, with 35 lights in each string. *There are
also a couple of lumps in the series lines. *They appear to be just
resistors, not diodes, as I measure the same value (~500 ohms) with
either polarity of my multimeter. * My guess is that the resistors are
there just to decrease the current so that the LEDs are not running
overrrated. *I am thinking of putting/rewiring the two strings
directly in series and then reducing the series resistors until I get
the same overall brightness of the new 70-light string. *Has anyone
done any experimenting like this?


* *Leave it alone. The forward voltage drop on white or blue LEDs is
higher than red or green, so that's why they chose *35 LEDs per string.
If you get too close to the actual line voltage and use lower
resistance, any spike will cause a high current surge through the
string. *If you aren't capable and willing to design and build a
constant current boost supply, you are wasting your time.


Good point about surge limiting, altho I am not sure if LEDs are any
more susceptible than tungsten filament lamps.


* *Tungsten has a time constant, and the resistance goes up as the
voltage increases. *LEDs are current operated at a lot more constant
voltage. *A few volt rise in the power line rasies the current flow.
Harmonics and spikes on the power line will cause higher peak current
flow in the LEDs. It would be like operating a Zener very close to it's
knee voltage with only a very low resistance to limit the current.

--
You can't have a sense of humor, if you have no sense.


.... and LED's are very intolerant of PIV voltage. Any AC use requires
diodes to block or shunt the other 1/2 cycle. I prefer the shunt
method as it does not require the protection diode to have an infinite
reverse resistance.
Cheers,
Roger
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Windmill wrote:

klem kedidelhopper writes:

On Dec 28, 5:49=A0am, "William Sommerwerck"
wrote:
"Jeff Liebermann" wrote in message

...

I do like Christmas lights, but they only last until the squirrels
are done chewing on the wires.

"Done", as in "thoroughly cooked"?

It would break your mother's heart if she knew you liked Christmas lights=

.


When I was 13 I reasoned that if you got a whole bunch of extension
cords and plugged them into various different outlets in the house,
then wired them all in series you could achieve infinite
possibilities. That was only topped by the 120.0 V to 6.0 volt step
down transformer I tried to wind on the metal frame of my bed. The
schematic showed 8 turns on the primary and 2 on the secondary.
Couldn't figure out why I lit up he room.....Lenny


It's astonishing that we survived until we were able to misunderstand
on a more sophisticated level.

Not as long ago as I would like it to be, I reasoned that since the
magnetron in a 1 megawatt (peak) early-warning radar presented an
impedance of about 500 ohms to the driving circuitry, a 1 kilowatt
microwave oven would use voltages of about 700 volts.


Have you ever been near, or inside a high power RADAR system? We
had two at Ft Rucker in the '70s Each ran 2 MW to track aircraft around
the base, and to the Gulf of Mexico. One was always being serviced
while the other was in use, to reduce the chances of both being down.
Both transmitters, and the high intensity RF from the antenna could kill
in less than a heartbeat.

A 25 KW RCA TTU-25B TV transmitter I rebuilt used 7 KV on the plates.


The meter I'd borrowed from a friend to look at his microwave sparked
internally (he claimed there was a blue glow, but he'd seen too many
mad scientist movies).



You're lucky that you didn't kill yourself.

I now know better, having better access to information!

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost



--
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klem kedidelhopper wrote:

On Dec 30, 6:13 pm, "Tom Del Rosso" wrote:
Jeff Liebermann wrote:
I do like Christmas lights, but they only last until the squirrels are
done chewing on the wires.


In NYC in the 70's squirrels were very rare in the winter, but the lights
lasted a day or two, until the neighbors had stolen half the bulbs.


There are no squirrels in NYC. The roaches ate them all. Lenny



Only the non-union roaches. The union roaches were on strike.


--
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"Michael A. Terrell" writes:

Have you ever been near, or inside a high power RADAR system? We
had two at Ft Rucker in the '70s Each ran 2 MW to track aircraft around
the base, and to the Gulf of Mexico. One was always being serviced
while the other was in use, to reduce the chances of both being down.
Both transmitters, and the high intensity RF from the antenna could kill
in less than a heartbeat.


Urban legend had it that someone had found a way, in the days before
vasectomies, to stand in front of a radar antenna for just long enough
to produce temporary sterilization.
But I didn't try that; doubtful if anyone would.

A 25 KW RCA TTU-25B TV transmitter I rebuilt used 7 KV on the plates.


My faulty assumption was that CW magnetrons used in microwaves had
similar characteristics (except for scale) to the pulsed
magnetrons used for radar. So I expected only 700 volts into 500 ohms.

The meter I'd borrowed from a friend to look at his microwave sparked
internally (he claimed there was a blue glow, but he'd seen too many
mad scientist movies).


You're lucky that you didn't kill yourself.


Not really. I hooked up the meter then stood well back before turning
on the microwave. (Wasn't really all that sure about the voltage
levels).

I now know better, having better access to information!

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost


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"Windmill" wrote in message
...
"Michael A. Terrell" writes:


Have you ever been near, or inside a high power RADAR system? We
had two at Ft Rucker in the '70s Each ran 2 MW to track aircraft around
the base, and to the Gulf of Mexico. One was always being serviced
while the other was in use, to reduce the chances of both being down.
Both transmitters, and the high intensity RF from the antenna could kill
in less than a heartbeat.


Unless you were standing near a tightly focused beam, this is unlikely.
Microwaves kill by overheating, and the first thing heated would be the
outer surface of your body, which probably wouldn't be lethal. It's more
likely you'd be blinded by having your corneas cooked.


Urban legend had it that someone had found a way, in the days before
vasectomies, to stand in front of a radar antenna for just long enough
to produce temporary sterilization. But I didn't try that; doubtful if

anyone
would.


You could just as well dip your testicles in a bowl of hot water for 15
minutes.


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William Sommerwerck wrote:

"Windmill" wrote in message
...
"Michael A. Terrell" writes:


Have you ever been near, or inside a high power RADAR system? We
had two at Ft Rucker in the '70s Each ran 2 MW to track aircraft around
the base, and to the Gulf of Mexico. One was always being serviced
while the other was in use, to reduce the chances of both being down.
Both transmitters, and the high intensity RF from the antenna could kill
in less than a heartbeat.


Unless you were standing near a tightly focused beam, this is unlikely.
Microwaves kill by overheating, and the first thing heated would be the
outer surface of your body, which probably wouldn't be lethal. It's more
likely you'd be blinded by having your corneas cooked.



Birds would drop dead if they flew too close to that RADAR antenna,
but the highest risk of death was from the high current, high voltage
power supplies in tube type microwave sources. High power RADAR tubes
were huge, when compared to the lowly Magnetron in an oven.


Urban legend had it that someone had found a way, in the days before
vasectomies, to stand in front of a radar antenna for just long enough
to produce temporary sterilization. But I didn't try that; doubtful if

anyone
would.


You could just as well dip your testicles in a bowl of hot water for 15
minutes.



That is used when Water boarding fails. ;-)


--
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"Michael A. Terrell" writes:


William Sommerwerck wrote:

"Windmill" wrote in message
...
"Michael A. Terrell" writes:


Have you ever been near, or inside a high power RADAR system? We
had two at Ft Rucker in the '70s Each ran 2 MW to track aircraft around
the base, and to the Gulf of Mexico. One was always being serviced
while the other was in use, to reduce the chances of both being down.
Both transmitters, and the high intensity RF from the antenna could kill
in less than a heartbeat.


Unless you were standing near a tightly focused beam, this is unlikely.
Microwaves kill by overheating, and the first thing heated would be the
outer surface of your body, which probably wouldn't be lethal. It's more
likely you'd be blinded by having your corneas cooked.



Birds would drop dead if they flew too close to that RADAR antenna,
but the highest risk of death was from the high current, high voltage
power supplies in tube type microwave sources. High power RADAR tubes
were huge, when compared to the lowly Magnetron in an oven.


I think you must be talking about much newer equipment than I worked
on.
Long ago, magnetrons (of a different design from the ones still used in
microwave ovens) were the only way to generate high peak powers, and
the oscillation frequency of a magnetron wasn't very stable.

Since then, I hear that high power klystrons have been used as
amplifiers in radar systems, and I believe there's a still newer tube
type which is used in the latest gear.

But as you say, the power supplies are and were very dangerous, needing
elaborate interlock systems to enhance safety.

Urban legend had it that someone had found a way, in the days before
vasectomies, to stand in front of a radar antenna for just long enough
to produce temporary sterilization. But I didn't try that; doubtful if

anyone
would.


You could just as well dip your testicles in a bowl of hot water for 15
minutes.



That is used when Water boarding fails. ;-)


The radar tale was probably meant as a warning which would have a
considerable effect on most young guys!

--
Windmill, Use t m i l l
J.R.R. Tolkien:- @ O n e t e l . c o m
All that is gold does not glister / Not all who wander are lost
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Windmill wrote:

"Michael A. Terrell" writes:

Birds would drop dead if they flew too close to that RADAR antenna,
but the highest risk of death was from the high current, high voltage
power supplies in tube type microwave sources. High power RADAR tubes
were huge, when compared to the lowly Magnetron in an oven.


I think you must be talking about much newer equipment than I worked
on.



The system was a few yeas old in '72, when I arrived. I think those
systems were custom built by Westinghouse. I worked on so many custom
and semi custom items in the Army that I don't remember, almost 40 years
later. The oldest I repaired was made and deployed during the Korean
war. They were so called 'Portable' systems.


Long ago, magnetrons (of a different design from the ones still used in
microwave ovens) were the only way to generate high peak powers, and
the oscillation frequency of a magnetron wasn't very stable.



Not that they weren't stable. They were powered with unfilterd DC,
which caused a wideband output. They are operated as a self excited
oscllator when used in a microwave, and as long as the thisng is in
band, the frequency or bandwitch doesn't really matter. Have you ever
read the MIT Rad Lab series of declassified W.W.-II books, or Slotnik's
RADAR Handbook?


Since then, I hear that high power klystrons have been used as
amplifiers in radar systems, and I believe there's a still newer tube
type which is used in the latest gear.



I've worked with 65 KW EEV Klystrons. A Comark with three of them,
on TV Ch 55 were located in Orange City Florida. They had just ordered
the transmitter when Kystrodes were introduced. Today, the TV
transmitters are all solid state.


But as you say, the power supplies are and were very dangerous, needing
elaborate interlock systems to enhance safety.



Not just the power supplies. The gates to get to the RADAR antenna
had multiple key switches to disable the entire system


Urban legend had it that someone had found a way, in the days before
vasectomies, to stand in front of a radar antenna for just long enough
to produce temporary sterilization. But I didn't try that; doubtful if
anyone
would.

You could just as well dip your testicles in a bowl of hot water for 15
minutes.


That is used when Water boarding fails. ;-)


The radar tale was probably meant as a warning which would have a
considerable effect on most young guys!



I saw dead birds in the parking lot fairly often, for the nine months
I was s tationed at that RADAR site.

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On Jan 3, 6:05*pm, "Michael A. Terrell"
wrote:

Windmill wrote:
Long ago, magnetrons (of a different design from the ones still used in
microwave ovens) were the only way to generate high peak powers, and
the oscillation frequency of a magnetron wasn't very stable.


* *Not that they weren't stable. *They were powered with unfilterd DC,
which caused a wideband output. *They are operated as a self excited
oscllator when used in a microwave, and as long as the thisng is in
band, the frequency or bandwitch doesn't really matter. *Have you ever
read the MIT Rad Lab series of declassified W.W.-II books, or Slotnik's
RADAR Handbook?


Isn't the frequency determined by the dimensions of the cavity the
energy is dumped into? Or does that tune it too broadly?
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spamtrap1888 wrote:

On Jan 3, 6:05 pm, "Michael A. Terrell"
wrote:

Windmill wrote:
Long ago, magnetrons (of a different design from the ones still used in
microwave ovens) were the only way to generate high peak powers, and
the oscillation frequency of a magnetron wasn't very stable.


Not that they weren't stable. They were powered with unfilterd DC,
which caused a wideband output. They are operated as a self excited
oscllator when used in a microwave, and as long as the thisng is in
band, the frequency or bandwitch doesn't really matter. Have you ever
read the MIT Rad Lab series of declassified W.W.-II books, or Slotnik's
RADAR Handbook?


Isn't the frequency determined by the dimensions of the cavity the
energy is dumped into? Or does that tune it too broadly?



The dimensions are the largest part of determining the frequency, but
it can be 'pulled' by voltage. Since it isn't run in CW mode in a
microwave, the oscillation has to start each time the plate voltage is
high enough on the unfiltered DC supply. The magnetron is designed for
the application, to keep it operating in the assigned band in this mode
of operation.


--
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Not that they weren't stable. They were powered with unfilterd DC,
which caused a wideband output. They are operated as a self excited
oscllator when used in a microwave, and as long as the thing is in
band, the frequency or bandwitch doesn't really matter.


Wasn't that an Eagles song? "Bandwitchy Woman"?


Isn't the frequency determined by the dimensions of the cavity
the energy is dumped into? Or does that tune it too broadly?


If I understand your misunderstanding... "Wideband" refers to the "spuriae"
generated by the unfiltered 60 Hz and its harmonics.


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William Sommerwerck wrote:

Not that they weren't stable. They were powered with unfilterd DC,
which caused a wideband output. They are operated as a self excited
oscllator when used in a microwave, and as long as the thing is in
band, the frequency or bandwitch doesn't really matter.


Wasn't that an Eagles song? "Bandwitchy Woman"?

Isn't the frequency determined by the dimensions of the cavity
the energy is dumped into? Or does that tune it too broadly?


If I understand your misunderstanding... "Wideband" refers to the "spuriae"
generated by the unfiltered 60 Hz and its harmonics.



AKA 'Phase Noise'.


--
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On Jan 5, 6:38*pm, "Michael A. Terrell"
wrote:
William Sommerwerck wrote:

Not that they weren't stable. They were powered with unfilterd DC,
which caused a wideband output. They are operated as a self excited
oscllator when used in a microwave, and as long as the thing is in
band, the frequency or bandwitch doesn't really matter.


Wasn't that an Eagles song? "Bandwitchy Woman"?


Isn't the frequency determined by the dimensions of the cavity
the energy is dumped into? Or does that tune it too broadly?


If I understand your misunderstanding... "Wideband" refers to the "spuriae"
generated by the unfiltered 60 Hz and its harmonics.


* *AKA 'Phase Noise'.


Ah.

Can you engineer a phase lock loop into a microwave oven?
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