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Rope Light Circuit...

B

Bret Cahill

Guest
The sealed-up-in-plastic power supply comes with the plug, 110v U.S. or 220v EU.

On a 110 v AC U. S. plug the output appears to be 110 v DC and 220 AC on a volt meter.

The LED part of the rope light plugs into the output of the power supply. It looks like two rails go the length of the LED section which can be cut every meter at a marked location. Some LEDs can burn out while the others remain lit. The LEDs are in parallel.

Do the LEDs run off the 220 AC or the 110 v DC?

The connector from the adapter to the rope has an orientation indicating it might be DC. If so is the 220 voltage just extraneous, part of a simple low power rectification?
 
R

Ralph Mowery

Guest
In article <894d6f11-0768-4b5f-a52e-9d2343c3a72cn@googlegroups.com>,
bretcahill@aol.com says...
The sealed-up-in-plastic power supply comes with the plug, 110v U.S. or 220v EU.

On a 110 v AC U. S. plug the output appears to be 110 v DC and 220 AC on a volt meter.

The LED part of the rope light plugs into the output of the power supply. It looks like two rails go the length of the LED section which can be cut every meter at a marked location. Some LEDs can burn out while the others remain lit. The LEDs are in parallel.

Do the LEDs run off the 220 AC or the 110 v DC?

The connector from the adapter to the rope has an orientation indicating it might be DC. If so is the 220 voltage just extraneous, part of a simple low power rectification?
Neither. The individual LEDs are around 1 to 3 volts depending on the
led type. There is a resistor to limit the current through them.

So comming down the rail on each side is a low voltage DC of around 12
to 24 volts. Often a switching supply is used so the voltage is not a
very good DC, but a DC with lots of ripple voltage. You can count the
number of leds in a section and get an idea of the voltage.

Usually each section will have a resistor and seveal leds in series.

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.

Leds operate on DC through them.
 
E

Eli the Bearded

Guest
In sci.electronics.basics, Ralph Mowery <rmowery28146@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
 
B

Bret Cahill

Guest
The sealed-up-in-plastic power supply comes with the plug, 110v U.S. or 220v EU.

On a 110 v AC U. S. plug the output appears to be 110 v DC and 220 AC on a volt meter.

The LED part of the rope light plugs into the output of the power supply. It looks like two rails go the length of the LED section which can be cut every meter at a marked location. Some LEDs can burn out while the others remain lit. The LEDs are in parallel.

Do the LEDs run off the 220 AC or the 110 v DC?

The connector from the adapter to the rope has an orientation indicating it might be DC. If so is the 220 voltage just extraneous, part of a simple low power rectification?







Neither. The individual LEDs are around 1 to 3 volts depending on the
led type. There is a resistor to limit the current through them.

So comming down the rail on each side is a low voltage DC of around 12
to 24 volts. Often a switching supply is used so the voltage is not a
very good DC, but a DC with lots of ripple voltage. You can count the
number of leds in a section and get an idea of the voltage.

Usually each section will have a resistor and seveal leds in series.

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.

Leds operate on DC through them.
LEDs can operate on AC, it\'s just not quite 50% of the time. Unless the flashing is undesirable, rectification seems redundant.

Also, if the goal is DC, how does the 220v AC appear as a by product?

A lower extraneous AC voltage might make sense but a higher voltage? That seems intentional.


Bret Cahill
 
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