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?