Another LED christmas string question...

Gonzowerke · Post by **Gonzowerke** » Sun Dec 21, 2008 9:57 am

What is the wiring diagram of, say, a phillips or GE string of LED lights?
Is there any resistor in there? I know the leds are running on AC, not DC, as when you swing a lit string around, you get a "wagon Wheel" effect due to the leds flashing at 60Hz. Is it simply all in series being fed straight 120vac?

Thanks!

Gonzo

photoguy · Post by **photoguy** » Sun Dec 21, 2008 12:18 pm

From tearing apart a few strings last year, I did find a few small resistors scattered through the bases of the string. Not every base, and not just the first or last one on the string.

For modeling purposes, I found it best just to strip all of the LED's out of the bases, and wire them up as individual units. DO NOT try to re-use the string of sockets. Once you start tearing it apart it is a serious safety concern to make sure you clip off the sockets and plugs from the string, and you don't try to wire it directly to a wall socket. It would be a very shocking experience.

Richard Baker · Post by **Richard Baker** » Sun Dec 21, 2008 1:06 pm

Target, CVS, Walgreens & Michael's all have low voltage LED light sets for less than $10- white, multi-colored, tiny- there is a lot out there. I have been picking up a few as I go around and they are already wired for battery power- much better that trying to adapt AC sets.

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dbhs · Post by **dbhs** » Thu Jan 15, 2009 10:28 pm

I'm doing some general research on LEDs as I'd like to use them in an upcoming project. I've heard about quality issues among the various manufacturers of LEDs. Would LEDs in an inexpensive set be reliable enough for permanently sealing inside a model? Would it be better to use the circuitry in a cheap set and swap out the LEDs with those of better quality? Thanks.

-Doug

Richard Baker · Post by **Richard Baker** » Thu Jan 15, 2009 10:35 pm

I have found the biggest problem with cheap LEDs is the cheap solder jobs connecting the pieces. To get the best result in a sealed unit you could buy some higher output LEDs and replace the originals.
On my Timeslip Galactica I will be using a stock string, but I am grouping all 18 together so if a couple faile I will still get the light I need.

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Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Fri Jan 16, 2009 4:22 am

Yellow and red LED are 1.8v-2.2v
Green and white LED are 3.2-3.4v

The strings are wired up in series so that the total voltage of
any set of LED in the string is 115v-120v in the US.
All LED are DC voltage, but the diodes only pass current in
one direction, so they are all actually blinking when connected to
AC current. Hence the "wagon wheel effect".

Richard Baker · Post by **Richard Baker** » Fri Jan 16, 2009 9:12 am

I use that battery powered versions myself- easier to set up a power supply in the model or base.

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Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Fri Jan 16, 2009 3:53 pm

Richard Baker wrote:I use that battery powered versions myself- easier to set up a power supply in the model or base.

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I Buy 3mm LED in 50 or 100 pc quantities w/resistors for 12v applications
4000mcd or greater for about 10cents apiece.
Just to guarantee I get what I want,... plus it's deductable as a business expense.

If you break the strings down to just the LED pieces, you have the
the same thing anyway, I don't need any of the wiring, battery
holders or sockets.