LED Christmas lights have a series lump, what is it for?
I have noticed that about half of the LED Christmas light strings have a "lump" about 1.5 inches long and 1/2 inch diameter in series with the lights, which have polarized sockets. I assume that it must either be a diode or a resistor or perhaps both. What puzzles me is what limits current and polarizes the AC into pulsating DC in the light strings that do not have any visible "lump"? Perhaps there are resistors built into each individual lamp, but the lamps that I have taken loose have the LED leads going directly out the bottom of the socket. And, I haven't seen any sign of any resistors built into the sockets themselves. Anyone know for sure what's going on??? |
LED Christmas lights have a series lump, what is it for?
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LED Christmas lights have a series lump, what is it for?
On 15/02/2016 08:13, N_Cook wrote:
On 15/02/2016 05:14, wrote: I have noticed that about half of the LED Christmas light strings have a "lump" about 1.5 inches long and 1/2 inch diameter in series with the lights, which have polarized sockets. I assume that it must either be a diode or a resistor or perhaps both. What puzzles me is what limits current and polarizes the AC into pulsating DC in the light strings that do not have any visible "lump"? Perhaps there are resistors built into each individual lamp, but the lamps that I have taken loose have the LED leads going directly out the bottom of the socket. And, I haven't seen any sign of any resistors built into the sockets themselves. Anyone know for sure what's going on??? RFI suppressor ferrite cylinder? LED xmas lights with their long wires and smps are one of the best ways of corrupting wifi connections. |
LED Christmas lights have a series lump, what is it for?
On Mon, 15 Feb 2016 10:44:02 +0000, N_Cook wrote:
On 15/02/2016 05:14, wrote: I have noticed that about half of the LED Christmas light strings have a "lump" about 1.5 inches long and 1/2 inch diameter in series with the lights, which have polarized sockets. I assume that it must either be a diode or a resistor or perhaps both. What puzzles me is what limits current and polarizes the AC into pulsating DC in the light strings that do not have any visible "lump"? Perhaps there are resistors built into each individual lamp, but the lamps that I have taken loose have the LED leads going directly out the bottom of the socket. And, I haven't seen any sign of any resistors built into the sockets themselves. Anyone know for sure what's going on??? RFI suppressor ferrite cylinder? LED xmas lights with their long wires and smps are one of the best ways of corrupting wifi connections. I really doubt that cheap communist chinese manufacturing would go to that expense... |
LED Christmas lights have a series lump, what is it for?
Jeff Lieberman,
The wiring web site was interesting in how poorly it was done, but didn't really give me any answers to my questions. |
LED Christmas lights have a series lump, what is it for?
On Thu, 18 Feb 2016 09:03:05 -0800 (PST), wrote:
Jeff Lieberman, The wiring web site was interesting in how poorly it was done, but didn't really give me any answers to my questions. Well, I indicated that I didn't have an easy answer. Basically, I would need to know what's inside the lump before making yet another guess(tm). It could be anything (diode, capacitor, ferrite bead, resistor, etc). The same components could also be molded into the power plug. Also, unless the series current limiter is in the plug or in the LED's, I don't see how it could be done without something inside the lump. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
LED Christmas lights have a series lump, what is it for?
I am sure there is nothing in the power plug, I have taken apart several of both types of LED light strings, and there is nothing in the plug except for fuses. I am guessing that maybe the internal diode resistance is enough to limit the current when there are enough bulbs to almost reach 120V just using the internal diode drops. I will have to count how many bulbs are in series in each of the two types of lights and see if that shows any pattern
I rebuild old Christmas light (filament and LED) sets that are given to our local recycle center and then donate the lights to local charities that have resale facilities, and I have several strings of each type in my rebuild boxes so that is mostly a matter of getting to it. I'll post the results after I have done my research. |
LED Christmas lights have a series lump, what is it for?
I took apart five individual LED Christmas light bulbs, from a string of lights that did not have a "glob" in series with the bulbs. Each of the lights had a really tiny resistor in series with the bulbs. The stripes and body color on the resistors were so small I could not tell which was the body and which were the stripes. My cheap HF multimeter said the actual resistors were 260 ohms. I didn't try to clip lead the bulbs into a working string of lights so I wasn't able to measure the forward drop across the LED diode itself. I will try that later this week when I work on some more LED light strings. Right now my repair shop is working on filament light strings.
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