This style of LED string used to be quite expensive, but it's clear that it lends itself to mass production well as the price has come crashing down quickly. This type of LED string has two lacquered copper wires with surface mount LEDs soldered in parallel along their length. The wires are obviously held tightly in parallel and formed into a flat topped peak that has the lacquer ground off. The wires seem to be pressed tightly against the back of a surface mount LED, soldered and then dipped in resin that encapsulates the LED and wires for strength and insulation. These may prove to be quite good for outdoor use as the connections are fully encapsulated in resin.
I was intrigued by a set of 100 LEDs designed for 12V, and wanted to see how they were wired. They have been divided into four sections of 25 parallel LEDs that are then connected in series to give a combined forward voltage of 12V (4 x 3V). I couldn't find a series resistor, so they are relying on the combined forward voltage and the knee/slope that gallium nitride LEDs have where they will have a forward voltage that typically varies between about 2.5 and 3.4V depending on the current passing through them.
The way the sections were hooked in series was clever. Both wires of the parallel circuit being cut, and one sections positive being connected to the others negative and the other wires just folded back and covered with heatshrink sleeve.

14 thoughts on “Analysis of a 100 led string of wire lights .”
  1. Avataaar/Circle Created with python_avatars sam sami says:

    Hi thank you for this helpful video. I was just thinking about this as i recently found them and i bought 4 of this (battery suplied 1.45meterea long) i used them for a project and i would like to kink all those 4 packs togethers and try to make something be powered by plug . Can you help me how i can do that. Is it fin if i jus link the end of each pack with other pack by sording cables? How i know which one is + and which is –

  2. Avataaar/Circle Created with python_avatars Iwona Podgrudna says:

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  3. Avataaar/Circle Created with python_avatars Flesz says:

    I have a question . I bought a christmas tree with white LEDs built in, and they only lasted 10 mins. When I tried to change the blinking mode it died. The power supply doesn't have any power output anymore, the info on the power supply says Urated=29V , Uout = 32V , Prated=15W . So I decided to do the power supply myself, I had old toroidal transformer and wound up enough wire to provide 30V . Now I ordered on ebay bridge rectifier KBPC3504 so this should sort out the AC to DC issue. Now I am not sure about the resistance needed, as my transformer is probably giving 10A on that 30V . And also not sure about capacitor, do I need any? How do I calculate the resistance needed considering the old PSU had 15W and 30V , which means 0.5A output. I would need to achieve the same output and not higher or the LEDs will burn .

  4. Avataaar/Circle Created with python_avatars Guy Riley says:

    I have a set of these very thin copper wire lights which is made up of 16 strings joined to one 12v 6W supply wire and designed to "cascade" down a christmas tree. Every 5 or so lights pulses on and off to create a "twinkle" effect. My question is would it be possible to fit a suitable dimmer, if so, what should I be looking for?

  5. Avataaar/Circle Created with python_avatars riley arendasky says:

    Hi! Love your videos. I have a question that you may be able to help with. I have a set of copper string lights that I am attaching outside to a tree. The lights are "waterfall" or "vine" lights. There are 10 strands all connected to a central point. Each strand consists of two wires. They appear to end with a simple cut. They are not soldered back on themselves. I attached it to a tree with staples. About halfway through, I checked it and it worked. At the end, I plugged it in, and none of the lights will light. Did I short the entire bunch of lights? If I did, how do you think I managed it and is it repairable? I have a soldering gun and novice level experience. I'd love to hear what you have to say!
    Thank you in advance

  6. Avataaar/Circle Created with python_avatars Martin Keast says:

    Hi Clive, what's the best way to make a 9 led panel say 4inx6in to illuminate a lithograph. ideally, it would need to be run on 3v

  7. Avataaar/Circle Created with python_avatars Mike Biddell says:

    I have five sets of these driven by a USB flasher. I want to drive the five sets so they flash in synchronism. How easy is that to do ???? Could one USB drive be buffered to achieve it ???

  8. Avataaar/Circle Created with python_avatars Wierdy1024 says:

    Your resistor is the ~50m of thin copper wire… You only need a resistance of a few ohms for sufficient current regulation.

  9. Avataaar/Circle Created with python_avatars Edit Kökényesi says:

    Hi. I have 300 led 12 volt fairy light string. And I have 12 independent short fairy light string with 20 leds and operated 2 pcs 3v battery. Can I connect thoose 2 type or can I connect the 12 small to a 1 long with plug in end to a wall cause the batteries die so fast.

  10. Avataaar/Circle Created with python_avatars Adolfo Fonseca says:

    I am trying to fix one of those 100 lights string, already tried all 3 wires possible connections in the RED and BLACK wires of the cable adapter. I am leaving a third wire disconnected as I compared it to a working string and is having that.

    Could someone explain how to solder this 3 wired string into the 2 wired adapter part with the females end.

    Thanks!

  11. Avataaar/Circle Created with python_avatars Jack Black says:

    I'm sure it's been asked but I have several of the 2 double aa battery style lights and see them often at dollar stores. I think you already covered the subject but I would like to know if connecting two of the 3v parallel strands in series would make it a 6v strand and if then could be run dimmer with a 5 volt usb? Think you may have answered the question saying the connections are not easy to distinguish but the lights I have are the bigger gauge wire more common style led string light and not the fairy lights. Would be nice to not have to buy a bunch of 3v power adapters, but guess I can start working with resistors too and learn something new. Love the videos and the way you tinker with lighting. You pop up in many google searches often times the only person to have answered the typical diy questions Ive had. Have a wonderful day!

  12. Avataaar/Circle Created with python_avatars Nodrog Awson says:

    I couldn't fathom out how these lights are to run on 12volts.
    Thank you for explaining the wiring.
    I always seem to find the answer from you.
    Much appreciated.

  13. Avataaar/Circle Created with python_avatars tupai62 says:

    what is their current, 12v ?Amp?

  14. Avataaar/Circle Created with python_avatars Gain PowerChannel says:

    can i put 300 lights or 3 sets by 100(10m) to 1 charger or to power surply.they are powered by 3 AA batery each now..but i want them be wired and if posible to power them with cable?!

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