RGB LED strip question
prof_braino
Posts: 4,313
I wanted color tunable LED lighting, so I ordered this from Ebay
5M 16.4FT Non-Waterproof RGB 5050 SMD Flexible LED Strips Lights 150 leds DC12V
The power module has four connections at one end, Red, Green, Blue, and common.
And they work as advertised, the LEDs display more or less all the colors of the rainbow, and they all display the same color, at least while they were on the roll.
Here's the thing: I mounted these on top of several cabinets, and had to run additional jumper wires to connect each segment. The instructions say 5M Max. With the extra jumper wires, it was about 7 meters total. I noticed now the color was different between the first LED in the first segment, and the last LED in the last segment. I figured it was because the length of the conductors affect the different voltages for the red green and blue differently, the first LED saw very short conductors, and the last LED saw very long conductors.
So here's what I did:
I disconnected the common at the original connector end. Then I ran a long piece of 18 gauge (just cause it was big, and handy) wire from the OTHER end of the strip back to the connector. Now, all three circuits pass through exactly the same amount of conductor. Now all the segments produce pretty much that same color again.
So here's my question: Is it really the different length of conductor that is causing this, or is it something else and there's a better way to do it?
Thanks!
5M 16.4FT Non-Waterproof RGB 5050 SMD Flexible LED Strips Lights 150 leds DC12V
The power module has four connections at one end, Red, Green, Blue, and common.
And they work as advertised, the LEDs display more or less all the colors of the rainbow, and they all display the same color, at least while they were on the roll.
Here's the thing: I mounted these on top of several cabinets, and had to run additional jumper wires to connect each segment. The instructions say 5M Max. With the extra jumper wires, it was about 7 meters total. I noticed now the color was different between the first LED in the first segment, and the last LED in the last segment. I figured it was because the length of the conductors affect the different voltages for the red green and blue differently, the first LED saw very short conductors, and the last LED saw very long conductors.
So here's what I did:
I disconnected the common at the original connector end. Then I ran a long piece of 18 gauge (just cause it was big, and handy) wire from the OTHER end of the strip back to the connector. Now, all three circuits pass through exactly the same amount of conductor. Now all the segments produce pretty much that same color again.
So here's my question: Is it really the different length of conductor that is causing this, or is it something else and there's a better way to do it?
Thanks!
Comments
then look at the IV curve for those LEDs... (I'm assuming no resistors in the strip?)
If there are no current-sharing resistors then keeping the forward voltages matched is a good idea (current matching
won't be brilliant but the human eye doesn't really notice). Alternatively power each strip from both ends so that only the
LEDs in the middle have drooping supplies.