Andrew Rossmann wrote:
[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]
In article . net,
says...
Yesterday I tried experimentally running one of the Forever Bright strings
off a bridge rectifier, no capactitor. It seemed only slightly brighter.
That's puzzling because although instantaneous brightness would stay the
same having twice as many flashes per unit time ought to seem something
like twice as bright.
Also, I noted an alleged 10V drop across the bridge (121V in, 111V out)
but I think this may be a figment of my DMM's imagination, perhaps unable
to give an accurate RMS reading of the pulsating full wave rectified DC. I
guess I should dig out my analog VOM. And maybe visually compare a couple
of C9's incandescent bulbs (considerably more current draw than an LED
string) on either side of the rectifier.
The brightness is mainly due to a greater on-percentage. It probably
depends on your sensitivity and ambient light. One easy test to see if
the rectifier is working properly is to wave a bulb sideways in front of
you. You should be able to see it turning on and off.
Yes, with the full wave rectifier you
will see very short off period (when
waving the
lamp). With half wave, you see the 50%
on and 50% off. I did notice a strange
thing in
the strings which I bought (LED Lights).
The one color 70 LED string (2 series
strings of
35) has the limit resistors in sockets
2,3,33,34 for the 1st half and
37,38,68,69 for the
second string of 35. You can actually
feel the heat on these sockets. I have
them on
a full wave rectifier. The multicolor
sting of 35 apparently has distributed
resistors
in every socket as there seems to be no
socket getting warm. Also, on their web
site
they mention that some color LEDs (white
and blue) are run at higher currents than
red. So, my guess is that there are
resistors in each socket.