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
Steve Kraus wrote:
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
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 ( firstname.lastname@example.org)
I wonder if instead of using a bridge, just put a big ol' capacitor on the
LED side of the string. That could smooth out the peaks and not add any
If not, plugging the string into a lamp dimmer would cut down the energy, if
the LEDs are getting too bright (and hot).
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! :)
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[This followup was posted to sci.electronics.repair and a copy was sent
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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
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
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
resistor should be 1/2 or 1 watt
(preferrable). Of course, you are
power, about 1/2 watt. Boy, do I have
too much time on my hands or what?
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.
My neighbors must be getting lazy because they have permanent outdoor
Christmas lights. Actually it's a good concept. Why not have them
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.
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.
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.
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.
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.
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