Hi everyone,

Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should not
penetrate and short out the circuit. I was wondering if anyone objects
to doing this. Also I was wondering if I should just not bother
sealing the connections.

Thanks,

Carl

wrote in message
oups.com...
Hi everyone,

Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should not
penetrate and short out the circuit. I was wondering if anyone objects
to doing this. Also I was wondering if I should just not bother
sealing the connections.

Can't hurt and the electrical tape manufacturer's love you! Merry XMAS.

wrote:
Hi everyone,

Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should not
penetrate and short out the circuit. I was wondering if anyone objects
to doing this. Also I was wondering if I should just not bother
sealing the connections.

Thanks,

Carl



I usually don't bother, but it certainly won't hurt anything. I've had a
few of the fused plugs on C9 strings burn up from water collecting in them.

Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should
not penetrate and short out the circuit. I was wondering if anyone
objects to doing this.

I object. Please don't do that anymore.

**kidding** I do it too.

On a related note can someone recommend a brand of LED xmas lights that are
as bright as typical miniature incandescents? I bought some last year but
they are noticably dimmer. I always put white lights on the roofline of
the house (using clips so each is positioned just so) and it looks nice.
But I'm one of those people for whom incandescent light looks yellowish so
white LED's look great--really really white--plus they look different than
anyone else's lights. I want them brighter though.

Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.

Steve Kraus wrote:
Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should
not penetrate and short out the circuit. I was wondering if anyone
objects to doing this.


I object. Please don't do that anymore.

**kidding** I do it too.

On a related note can someone recommend a brand of LED xmas lights that are
as bright as typical miniature incandescents? I bought some last year but
they are noticably dimmer. I always put white lights on the roofline of
the house (using clips so each is positioned just so) and it looks nice.
But I'm one of those people for whom incandescent light looks yellowish so
white LED's look great--really really white--plus they look different than
anyone else's lights. I want them brighter though.

[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article ,
says...
On a related note can someone recommend a brand of LED xmas lights that are
as bright as typical miniature incandescents? I bought some last year but
they are noticably dimmer. I always put white lights on the roofline of
the house (using clips so each is positioned just so) and it looks nice.
But I'm one of those people for whom incandescent light looks yellowish so
white LED's look great--really really white--plus they look different than
anyone else's lights. I want them brighter though.

I have some ForverBright sets. The 35-light sets are a single circuit.
I put a bridge rectifier in a small outlet box with a combo
switch/outlet. The rectifier came from my junk box, and is a giant 1.5"
or so square with a bolt hole through middle, way overkill. You could
obviously use something much smaller. Just don't forget a fuse rated at
or below the rectifier's rating.

Running off of unfiltered 120V DC, it is noticeably brighter, and no
obvious flicker. You could string several sets together. The newer sets
also have a nicer green. One set is older, and the green is dim and sort
of that puke lime-green color.

Be careful of longer sets. I have a 70-light set, and it is basically
two 35-light sets connected with opposite polarity. Running on DC, it's
one half or the other lit. I haven't looked close at it yet to see if
it's possible to reverse one circuit so it would be DC friendly.

Some sets run off of a transformer. They probably work similar to the
above. You'd just need a DC supply at the right voltage and current.

--
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.att.net/~andyross

Art Todesco wrote:
Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.

You are really fast with that stop watch. :-)

--
Joseph Meehan

Dia duit

Steve Kraus wrote:
Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should
not penetrate and short out the circuit. I was wondering if anyone
objects to doing this.

I object. Please don't do that anymore.

**kidding** I do it too.


I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K

I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K


My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
built in?

30 years ago we lived in a neighborhood where the homeowners were
shuned if they didn't get the lights down by say Feb 1.

Beachcomber

The town where I live has a March or
April 1st ordinance for
Christmas decorations/lights removal,
although I have seen
lights up all year on some houses. BTW,
some colored lights will
loose their color much faster if left
out all year.

Beachcomber wrote:
I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K



My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
built in?

30 years ago we lived in a neighborhood where the homeowners were
shuned if they didn't get the lights down by say Feb 1.

Beachcomber

Joseph Meehan wrote:
Art Todesco wrote:

Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.


You are really fast with that stop watch. :-)

No, but, if you move your head, you can
definitely see it.
And, it is irritating to some.

"Joseph Meehan" writes:

Art Todesco wrote:
Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.

You are really fast with that stop watch. :-)

Once you've seen a few pulsing LEDs, it's easy to tell. There are
only two common possitiblities - full wave or halfwave and they
are trivial to tell apart. There's no microcomputer in there to
produce other rep rates!

--- sam | Sci.Electronics.Repair FAQ: 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 Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

Andrew Rossmann wrote:
[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article ,
says...

On a related note can someone recommend a brand of LED xmas lights that are
as bright as typical miniature incandescents? I bought some last year but
they are noticably dimmer. I always put white lights on the roofline of
the house (using clips so each is positioned just so) and it looks nice.
But I'm one of those people for whom incandescent light looks yellowish so
white LED's look great--really really white--plus they look different than
anyone else's lights. I want them brighter though.


I have some ForverBright sets. The 35-light sets are a single circuit.
I put a bridge rectifier in a small outlet box with a combo
switch/outlet. The rectifier came from my junk box, and is a giant 1.5"
or so square with a bolt hole through middle, way overkill. You could
obviously use something much smaller. Just don't forget a fuse rated at
or below the rectifier's rating.

Running off of unfiltered 120V DC, it is noticeably brighter, and no
obvious flicker. You could string several sets together. The newer sets
also have a nicer green. One set is older, and the green is dim and sort
of that puke lime-green color.

Be careful of longer sets. I have a 70-light set, and it is basically
two 35-light sets connected with opposite polarity. Running on DC, it's
one half or the other lit. I haven't looked close at it yet to see if
it's possible to reverse one circuit so it would be DC friendly.

Some sets run off of a transformer. They probably work similar to the
above. You'd just need a DC supply at the right voltage and current.

Using the full wave rectifier without
any other current limiting could, depending
on the wiring, put too much current
through the string and shorten the LED life.
But, that said, it's probably not that
significant. And, as you pointed out,
they are somewhat brighter. I have a
set of 70 "L.E.D. Lights" that is actually
2 sets of 35, not alternated, but 35 in
a row, followed by 35 more. One
diode string is in one direction and the
other is opposite. A full wave bridge on
this set will cause 35 light not to
light unless you modify the wiring. I
tried wiring
all 70 lights in one series circuit
(with the diodes in the same direction)
and it was
much too dim even through the rectifier
bridge. Wiring the 2 groups of 35 in
parallel with the diodes in the same
direction, works but the string has a much
higher through current. A series
resistor of about 700 ohms corrects
this. The
resistor should be 1/2 or 1 watt
(preferrable). Of course, you are
wasting this
power, about 1/2 watt. Boy, do I have
too much time on my hands or what?

"Art Todesco" wrote in message
...
Plus, they blink! I don't understand why they don't put in full wave
rectifiers.
Yes I do, it's all $$$$, but I'd gladly pay an extra $1 for the rectifier.
Most of them that I have seen are on for 120th of a second and off for the
same.

SNIP

Mounting a hefty rectifier bridge in a box with an outlet is something that
you could do yourself for a few dollars. I'd also install a DPDT switch so
you could change the polarity of the output.

TKM

"Art Todesco" wrote in message
. ..
The town where I live has a March or April 1st ordinance for
Christmas decorations/lights removal, although I have seen
lights up all year on some houses. BTW, some colored lights will
loose their color much faster if left out all year.

Beachcomber wrote:
I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K



My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
built in?

30 years ago we lived in a neighborhood where the homeowners were
shuned if they didn't get the lights down by say Feb 1.

Beachcomber


The National Electrical Code now says (Article 590.3) that temporary holiday
decorative lighting can only stay up for 90 days. Don't know how many NEC
lighting police are around to check, but the stuff does deterioriate
especially from moisture and UV in sunlight.

TKM

Art Todesco wrote:
Joseph Meehan wrote:

Art Todesco wrote:

Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.



You are really fast with that stop watch. :-)

No, but, if you move your head, you can definitely see it.
And, it is irritating to some.


Yes it really is very noticeable, it was my main objection to LED
lights, but I picked up a pack of Philips LED's this year since they
were on sale and they're fairly bright so I'm gonna solder a bridge
rectifier into them just after the plug and seal it in heatshrink tubing.

I can see the 30hz flicker from those LED strings. (60hz rectified
with one diode chops half the sine wave in half). Love the low power
but not the flickers. Drives me nuts and hard on my eye.

Cheers, Wizard

Beachcomber wrote:
I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K


My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
built in?

....
Beachcomber

My neighbor had a small unrelated fire in the middle of the summer. The
fire department had the fire out in a few minutes with minimal damage to
their home. However they say the Christmas lights on it and put up an unfit
for occupancy sign and told them the sign would come down after they had
removed all the Christmas lights. It seems they have had problems with them
from people who have left them up all year. They got the lights down the
same day and they were back in their home the same day, with just a little
smoke and some repair work to the third floor.


--
Joseph Meehan

Dia duit

Are you the Art Todesco from Bell Labs??

H. R.(Bob) Hofmann

Are you the Art Todesco from Bell Labs??

H. R.(Bob) Hofmann

(Jason D.) writes:

I can see the 30hz flicker from those LED strings. (60hz rectified
with one diode chops half the sine wave in half). Love the low power
but not the flickers. Drives me nuts and hard on my eye.

Still 60 Hz.

--- sam | Sci.Electronics.Repair FAQ: 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 Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

Jason D. wrote:

I can see the 30hz flicker from those LED strings. (60hz rectified
with one diode chops half the sine wave in half). Love the low power
but not the flickers. Drives me nuts and hard on my eye.

If the 60 Hz (as others have corrected you) flicker bothers you how do you
watch TV (59.97 Hz vertical) or go to the movies (48 Hz ficker rate)?

On Mon, 21 Nov 2005 05:16:48 GMT, Steve Kraus
wrote:

Jason D. wrote:

I can see the 30hz flicker from those LED strings. (60hz rectified
with one diode chops half the sine wave in half). Love the low power
but not the flickers. Drives me nuts and hard on my eye.

If the 60 Hz (as others have corrected you) flicker bothers you how do you
watch TV (59.97 Hz vertical) or go to the movies (48 Hz ficker rate)?

Thanks for the correction.

60hz is what I can still see on monitors at 60hz and LEDs on AC
especially LED xmas strings. Bugs me.

TVs CRT has phorphors that is too slow to make it barely objectable.

When time permits I'm taking down two old fluorescents down was
magnetic ballast & old housings and put up new one with electronic
ballasts and proper housings that reflects lights towards floor.
These items are already bought and waiting to put up.

Cheers, Wizard

If the 60 Hz (as others have corrected you) flicker bothers you how do you
watch TV (59.97 Hz vertical) or go to the movies (48 Hz ficker rate)?


Have you actually seen LED xmas lights with this in person? They have a
50% duty cycle and zero phosphor persistance, the flicker is not subtle,
particularly if you move your eyes and catch the lights in your
peripheral vision. A TV does flicker, but the phosphor persistance makes
it far less apparent. A computer monitor with low persistance phosphors
running at 60Hz is unbearable though, instant headache.

"Joseph Meehan" wrote in
m:

Beachcomber wrote:
I don't object but then I don't see the point in doing it either. I
haven't done it ever (over 30 years), put out lots of lights in the
past, have had them up for a month, never had a short. Looks like
wasted time/effort and make a mess pulling them down.

Harry K


My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
built in?

...
Beachcomber

My neighbor had a small unrelated fire in the middle of the
summer. The
fire department had the fire out in a few minutes with minimal damage
to their home. However they say the Christmas lights on it and put up
an unfit for occupancy sign and told them the sign would come down
after they had removed all the Christmas lights. It seems they have
had problems with them from people who have left them up all year.
They got the lights down the same day and they were back in their home
the same day, with just a little smoke and some repair work to the
third floor.



The X-mas lights wire insulation probably gets degraded by UV exposure,or
damaged by weathering. Maybe dirt and moisture gets into sockets,corrosion
creates resistance and new,undesirable current paths.

--
Jim Yanik
jyanik
at
kua.net

It's a dangerous practice. If any moisture gets in, it will stay
there and do more damage than if the connection were left exposed.

wrote:
Hi everyone,

Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should not
penetrate and short out the circuit. I was wondering if anyone objects
to doing this. Also I was wondering if I should just not bother
sealing the connections.

Thanks,

Carl

James Sweet wrote:


If the 60 Hz (as others have corrected you) flicker bothers you how do
you watch TV (59.97 Hz vertical) or go to the movies (48 Hz ficker rate)?



Have you actually seen LED xmas lights with this in person? They have a
50% duty cycle and zero phosphor persistance, the flicker is not subtle,
particularly if you move your eyes and catch the lights in your
peripheral vision. A TV does flicker, but the phosphor persistance makes
it far less apparent. A computer monitor with low persistance phosphors
running at 60Hz is unbearable though, instant headache.

It prolly wouldn't take a very big electrolytic capacitor to level those
current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for all
the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

It prolly wouldn't take a very big electrolytic capacitor to level those
current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for all
the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it to
120Hz flicker, pretty much not noticeable unless you scan your eyes past
it quickly.

James Sweet wrote:



It prolly wouldn't take a very big electrolytic capacitor to level
those current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for all
the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it to
120Hz flicker, pretty much not noticeable unless you scan your eyes past
it quickly.

My thinking wuz that by using just a cap, you wouldn't change the total
energy delivered to the string of LEDs significantly, but with full wave
rectification you'd double it and possibly blow an LED if the original
design had them powered pretty close to their safe limit. Capice?

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

For an example of overdone xmas decorations, see:

http://media.putfile.com/WizardsofWinter-SM

(broadband connection suggested)

--
Rich Greenberg Marietta, GA, USA richgr atsign panix.com + 1 770 321 6507
Eastern time. N6LRT I speak for myself & my dogs only. VM'er since CP-67
Canines:Val, Red & Shasta (RIP),Red, husky Owner:Chinook-L
Atlanta Siberian Husky Rescue. www.panix.com/~richgr/ Asst Owner:Sibernet-L

Jeff Wisnia wrote:
James Sweet wrote:



It prolly wouldn't take a very big electrolytic capacitor to level
those current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for
all the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it to
120Hz flicker, pretty much not noticeable unless you scan your eyes
past it quickly.


My thinking wuz that by using just a cap, you wouldn't change the total
energy delivered to the string of LEDs significantly, but with full wave
rectification you'd double it and possibly blow an LED if the original
design had them powered pretty close to their safe limit. Capice?

Jeff

Good thought! But you have to put a
diode somewhere to protect the
electrolytic capacitor from seeing AC.
I guess you could "sacrifice" the
1st LED and put the capacitor after it.
But, there are parallel and/or series
resistors in the sockets, so you have to
be carefull. A separate diode
would probably be best.

Art Todesco wrote:

Jeff Wisnia wrote:

James Sweet wrote:



It prolly wouldn't take a very big electrolytic capacitor to level
those current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for
all the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it to
120Hz flicker, pretty much not noticeable unless you scan your eyes
past it quickly.



My thinking wuz that by using just a cap, you wouldn't change the
total energy delivered to the string of LEDs significantly, but with
full wave rectification you'd double it and possibly blow an LED if
the original design had them powered pretty close to their safe limit.
Capice?

Jeff

Good thought! But you have to put a diode somewhere to protect the
electrolytic capacitor from seeing AC. I guess you could "sacrifice" the
1st LED and put the capacitor after it. But, there are parallel and/or
series
resistors in the sockets, so you have to be carefull. A separate diode
would probably be best.

That shows another this Jew doesn't know about Xmas, I've never examined
a string of LED lights to determine just how they work. G

I'd assumed there was a half wave rectifier and maybe a series resistor
there already there, to avoid exceeding the LED's PIV ratings.

But maybe they avoid that with a parallel diode across each LED and a
single series resistor for the whole string, that's similar to what I
found inside one of our white LED nightlights when it started acting
funny because the LED was having a nervous breakdown. (It stayed dark
even though plugged in, but flickered on when I switched an inductive
load on the same circuit - a bathroom vent fan.) Soldering in a new LED
fixed that sucker.

Anyway, you got my point, full wave rectification would most likely
double the power dissipated in the LEDs if everything else in the
circuit stayed the same.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

Jeff Wisnia wrote:
Art Todesco wrote:

Jeff Wisnia wrote:

James Sweet wrote:



It prolly wouldn't take a very big electrolytic capacitor to level
those current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for
all the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it to
120Hz flicker, pretty much not noticeable unless you scan your eyes
past it quickly.




My thinking wuz that by using just a cap, you wouldn't change the
total energy delivered to the string of LEDs significantly, but with
full wave rectification you'd double it and possibly blow an LED if
the original design had them powered pretty close to their safe
limit. Capice?

Jeff

Good thought! But you have to put a diode somewhere to protect the
electrolytic capacitor from seeing AC. I guess you could "sacrifice"
the
1st LED and put the capacitor after it. But, there are parallel
and/or series
resistors in the sockets, so you have to be carefull. A separate diode
would probably be best.


That shows another this Jew doesn't know about Xmas, I've never examined
a string of LED lights to determine just how they work. G

I'd assumed there was a half wave rectifier and maybe a series resistor
there already there, to avoid exceeding the LED's PIV ratings.

But maybe they avoid that with a parallel diode across each LED and a
single series resistor for the whole string, that's similar to what I
found inside one of our white LED nightlights when it started acting
funny because the LED was having a nervous breakdown. (It stayed dark
even though plugged in, but flickered on when I switched an inductive
load on the same circuit - a bathroom vent fan.) Soldering in a new LED
fixed that sucker.

Anyway, you got my point, full wave rectification would most likely
double the power dissipated in the LEDs if everything else in the
circuit stayed the same.

Jeff

Adding a single diode and capacitor will
also increase the current because the
capacitor
will bring the DC voltage up to the peak
value of the AC line, usually considered
to be 177 volts. As I had a string of
70 (2 series circuits in the same
direction) on
the bench, I tried a single diode and
capactor. With a capacitor as small as
2.3uf,
the string current still went up
significantly and the LEDs got much
brighter. BTW,
in the stores they have a display string
(5 or 6 LEDs) with a momentary button to
show how they look. No blinking here as
this display is run on a battery burried in
the cardboard display.

Art Todesco wrote:

Jeff Wisnia wrote:

Art Todesco wrote:

Jeff Wisnia wrote:

James Sweet wrote:



It prolly wouldn't take a very big electrolytic capacitor to level
those current pulses out, huh?

Easy to do fer your own strings I guess, but that doesn't help for
all the others you have to look at.

Fortunately that 60 Hz flicker rate is above what triggers
photosensitive epilepsy in most persons sensitive to that.

http://www.epilepsy.org.uk/info/photo.html

Jeff




Don't even need a capacitor, a simple bridge rectifier changes it
to 120Hz flicker, pretty much not noticeable unless you scan your
eyes past it quickly.





My thinking wuz that by using just a cap, you wouldn't change the
total energy delivered to the string of LEDs significantly, but with
full wave rectification you'd double it and possibly blow an LED if
the original design had them powered pretty close to their safe
limit. Capice?

Jeff

Good thought! But you have to put a diode somewhere to protect the
electrolytic capacitor from seeing AC. I guess you could
"sacrifice" the
1st LED and put the capacitor after it. But, there are parallel
and/or series
resistors in the sockets, so you have to be carefull. A separate diode
would probably be best.



That shows another this Jew doesn't know about Xmas, I've never
examined a string of LED lights to determine just how they work. G

I'd assumed there was a half wave rectifier and maybe a series
resistor there already there, to avoid exceeding the LED's PIV ratings.

But maybe they avoid that with a parallel diode across each LED and a
single series resistor for the whole string, that's similar to what I
found inside one of our white LED nightlights when it started acting
funny because the LED was having a nervous breakdown. (It stayed dark
even though plugged in, but flickered on when I switched an inductive
load on the same circuit - a bathroom vent fan.) Soldering in a new
LED fixed that sucker.

Anyway, you got my point, full wave rectification would most likely
double the power dissipated in the LEDs if everything else in the
circuit stayed the same.

Jeff

Adding a single diode and capacitor will also increase the current
because the capacitor
will bring the DC voltage up to the peak value of the AC line, usually
considered
to be 177 volts. As I had a string of 70 (2 series circuits in the same
direction) on
the bench, I tried a single diode and capactor. With a capacitor as
small as 2.3uf,
the string current still went up significantly and the LEDs got much
brighter. BTW,
in the stores they have a display string (5 or 6 LEDs) with a momentary
button to
show how they look. No blinking here as this display is run on a
battery burried in
the cardboard display.


All sounds reasonable, maybe some more LEDs in the string and a cap
large enough to remain charged close to peak voltage would be an
economical way to avoid *any* flicker. G

I think we've about "saucered and blowed"* this one by now, but I am
curious about how those series strings handle the reverse voltage across
the LEDs. Do they have diodes or resistors across each one or do they
just depend upon the summed inverse breakdown voltages keeping the
reverse current from ever getting large enough to blow an LED? I'm
guessing maybe that's it, do ya happen to know the answer?

Jeff

* An old "down Maine" expression referring to method of cooling a too
hot cup of coffee by pouring some into the saucer and blowing across it,
returning it to the cup when it's ready to drink.

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."

I think we've about "saucered and blowed"* this one by now, but I am
curious about how those series strings handle the reverse voltage across
the LEDs. Do they have diodes or resistors across each one or do they
just depend upon the summed inverse breakdown voltages keeping the
reverse current from ever getting large enough to blow an LED? I'm
guessing maybe that's it, do ya happen to know the answer?



They depend on the latter, don't think for an instant that these things
are over-engineered, or even well engineered.

Really though, in practice I've found LED's to be far more tolerant of
reverse voltage than the specs would indicate.

In article , Steve Kraus
wrote:
Every Christmas when I hang my lights I seal all male/female
connections between cords with electrical tape so that water should
not penetrate and short out the circuit. I was wondering if anyone
objects to doing this.

I object. Please don't do that anymore.

**kidding** I do it too.

On a related note can someone recommend a brand of LED xmas lights that are
as bright as typical miniature incandescents? I bought some last year but
they are noticably dimmer. I always put white lights on the roofline of
the house (using clips so each is positioned just so) and it looks nice.
But I'm one of those people for whom incandescent light looks yellowish so
white LED's look great--really really white--plus they look different than
anyone else's lights. I want them brighter though.

Check out the Philips brand ones at Target.

They resemble the Forever Bright ones of the past 2-3 years. The
manufacturer mentioned on the package sounds familiart to me.
However, LEDs get improved gradually over the years, and I suspect they
also had to get brighter to get Philips to put their name on them.

At Target, they show some in operation - see if they're bright enough
for you.
I saw some with bare LEDs - those had somewhat narrow beams and were
weak outside their beams, while ones with "bulbs" over the LEDs shone more
equally in all directions.

- Don Klipstein )

In article 2z3gf.3613$kw2.1313@trnddc05, James Sweet wrote:
Art Todesco wrote:
Joseph Meehan wrote:

Art Todesco wrote:

Plus, they blink! I don't understand
why they don't put in full wave rectifiers.
Yes I do, it's all $$$$, but I'd gladly
pay an extra $1 for the rectifier.
Most of them that I have seen are on for
120th of a second and off for the
same.



You are really fast with that stop watch. :-)

No, but, if you move your head, you can definitely see it.
And, it is irritating to some.


Yes it really is very noticeable, it was my main objection to LED
lights, but I picked up a pack of Philips LED's this year since they
were on sale and they're fairly bright so I'm gonna solder a bridge
rectifier into them just after the plug and seal it in heatshrink tubing.

Make sure the LEDs don't overheat from getting twice as much average
current! But if nothing goes wrong, they will not only not flicker but
they will also be brighter.

Keep in mind that if they are going to overheat, they may not do so
quickly.
One thing that can happen is "thermal runaway" - where higher
temperature makes the LEDs more conductive, and this situation reinforces
itself. This may wait until a moment when the line voltage or the ambient
temperature is higher.
Keep in mind that such a modification voids UL certification and
increases your liability should a fire start - even if a flaw in the
product was a contributing factor to the fire.

- Don Klipstein )

In article . net, Steve
Kraus wrote:
Jason D. wrote:

I can see the 30hz flicker from those LED strings. (60hz rectified
with one diode chops half the sine wave in half). Love the low power
but not the flickers. Drives me nuts and hard on my eye.

If the 60 Hz (as others have corrected you) flicker bothers you how do you
watch TV (59.97 Hz vertical) or go to the movies (48 Hz ficker rate)?

I sometimes see flicker in TVs and monitors set to 60 Hz. I usually see
flicker in monitors set to 56 Hz.

I also only sometimes see LED lights flickering when they have 60 Hz
flicker. I suspect that the flicker gets more visible when the light
source is more intense - possibly explaining why LEDs are more likely to
visibly flicker at 60 Hz than TVs and monitors are.

Movies have a high duty cycle and a much shorter offtime than halfwave
rectified LEDs.

- Don Klipstein )

I really wanted to buy some LED last year, they were real cheap at an
after Xmas sale at a Nursery. The white ones, (the only ones I was
interested in) were too "cool" for my taste. I love the yellowy glow
of regular incandescent "white" lights, seems homey, warm & inviting.
The LED's looked harsh & "office-light" like for my tastes so I took
a pass.

FWIW... they must be popular, as from what I could see Target or mass
marketers, from what I could see, sold out before Christmas

I hope they soon come out with a warmer version, for I can't wait to be
done with cheap incandescent xmas lights buring out and driving me
absolutely crazy. .

Don Klipstein wrote:
I sometimes see flicker in TVs and monitors set to 60 Hz. I usually see
flicker in monitors set to 56 Hz.

I also only sometimes see LED lights flickering when they have 60 Hz
flicker. I suspect that the flicker gets more visible when the light
source is more intense - possibly explaining why LEDs are more likely to
visibly flicker at 60 Hz than TVs and monitors are.

I'm going to say one word, and you decide if you still like your theory.

Persistence.

--
If John McCain gets the 2008 Republican Presidential nomination,
my vote for President will be a write-in for Jiang Zemin.