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Can't identify LED

Aidan Carrigan

Nov 14, 2016
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Hi, last year I was at Disney world and saw they had a certain type of LED Christmas light string where each bulb (without the help of a controller) would switch colors between red and green with a second or two in beteeen each color change. There were only two leads coming out of each bulb and again there was no controller of any sort on the string, each bulb was timed slightly different from the others as so they did not all change color at the same time. Does anybody know where I could buy those types of bulbs at? Thanks

The lights in question:
 

Audioguru

Sep 24, 2016
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Most electronic parts distributors list and stock bi-color LEDs. The LEDs are wired back-to-back with reversed polarity on one so the polarity causes the color change.
Here is one from Digikey:
 

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Audioguru

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An RGB color changing LED has a microprocessor inside to change the 3 colors. Its program is fixed and cannot be changed. Some cheap Chinese tea-lights, solar garden lights and Christmas ornaments use them. They are completely different to the red-green bi-color LED.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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However, from the description, the OP is after color changing LEDs, not bicolour LEDs.
 

Audioguru

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The first video is titled Red Green LEDs and clearly shows each LED switching from red to green to red to green over and over, no blue. The second video has the LEDs too far away to see what they are doing. I think they are red blue bicolor LEDs.
 

Aidan Carrigan

Nov 14, 2016
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Thanks for the responses! Say I were to buy some, how would I get 50 of them to run in a Christmas light string? What would the specs of the bulb need to be and the resistors that go with it?
 

Aidan Carrigan

Nov 14, 2016
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I know that s4 lights makes the strings however they are a custom order and there minimum order for custom strings costs over $5k :( certainly out of my budget o_O
 

Audioguru

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The LEDs have or might have (Chinese you know) a voltage of 3.2V to 3.4V and a current of 10mA to 20mA (ebay is just guessing). Then you can use a 5V supply and connect each one in series with a resistor of (5V - 3.2V)/20mA= 90 ohms (use 91 ohms).If the LEDs are actually 3.4V then their current will be (5V - 3.4V)/91 ohms= 17.6mA. I do not know if you can connect three of these switching LEDs in series so that you can use a 12V supply.
 

(*steve*)

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Then you can use a 5V supply and connect each one in series with a resistor

Ask the seller. Sometimes these types of LEDs can run off a straight 5V, other times they need a resistor.

I do not know if you can connect three of these switching LEDs in series so that you can use a 12V supply.

It may work placing three in series, but (in the case with flashing LEDs, for example) their current varies so much that they can be used to flash other LEDs in series with them.
 
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