In sci.electronics.basics, Ralph Mowery <
rmower...@earthlink.net> wrote:
> Leds are really current sensitive and not voltage . The led will take
> form 1 to 3 volts to start to light up. However if you do not limit the
> current the led burns up. So you put a few leds in series with a
> resistor and supply a few more volts than the leds require to light to
> the brightness desired.
About ten years ago I bought an LED candelabra bulb which lasted for
about five years before dying. I took it apart to see if I could figure
out what's wrong (mind you, I'm not an electronics wizard). The power
adapter part, which I suspected to be the problem, was turning out 150v
DC. The whole thing had a circuit even I could decipher. There was a
simple recifier with four diodes, two capacitors, and three resistors.
Inspection of the light board showed that it had all 20 (old-school T1
3/4 size through-hole soldered) LEDs in series. I suspect that one of
them failed, and that's what killed the whole.
I don't think they make LED bulbs like that any more. More recent bulbs
I've taken apart have been much different inside.
Elijah
------
saved the LEDs but hasn't used them yet