RGB 5050 LED strip FAR too blue/green (not enough red)? - Page 1
Forum section: electronics / projects

author: iamdarkyoshi
author_rank: Frequent Contributor
timestamp: November 11, 2015, 04:27:33 am
content: So I bought a 5M RGB LED strip with a controller and remote for an amazing $2.60 USD. We are going to use it for cabinet lighting in the kitchen. We bought some "Warm White" LED strips and they ended up being cold white (seller refunded part of the order and we kept the LED tape because the picture and description clearly said Warm White) so that's when we bought the RGB strips. I figured we should be able to somewhat "tune" the color we wanted, as well as do colors for parties, ect. So I powered them up, and the red is much dimmer than the green/blue. Normally this would not be too much of a concern, I could just turn down the green/blue with the remote. However, I need as much light as I can get from these, and they are not terribly bright to begin with. I tried turning both of them down, and by that point, the strip is really quite dim. My 30 year old multimeter (not true RMS) measured about 7 volts on the blue and green when the red was at 12v and the light looked cool white. So obviously the red is either being driven too LOW, or the green/blue are too high.I thought maybe I could run the controller at a higher voltage and put big-ass power resistors on the green and blue channels, making the red brighter by comparison.Is this a good idea? Obviously I would need to measure the current draw on a section of tape to begin with, I should see a max of 20mA per section of three series chips? or do 5050 LEDs run at a higher power?Edit: So the green and blue are running at about 16.5mA, and the reds at 17.5mAThanks guys!

author: ajb
author_rank: Super Contributor
timestamp: November 11, 2015, 05:22:31 am
content: I think this may be a case of "what do you want for $2.60?" It could be that the wrong resistors were fitted for the red LEDs (I've gotten RGB LED tape where some segments had off colors because one of the resistors in the segment was wrong). You could try doing what you describe, or you could try your luck with a different roll of tape. Maybe splurge on one of the $12 rolls. Even with the best RGB tape you can buy, though, RGB white is never going to be as good for illumination as a proper white source, and the color rendering under RGB white is always going to be terrible (food will look weird). If these are for illumination and not just accent, I'd strongly consider going for RGBW tape, or fit some white tape along with the RGB. Use the white for illumination, and the RGB for party time.

author: Psi
author_rank: Super Contributor
timestamp: November 11, 2015, 05:31:32 am
content: The red channel should draw significantly higher current for two reasons.- The red led forward voltage is lower, 2V vs 3-4V for other colors. So it gets less energy for the same current- The eye is less sensitive to red so you need more of it to make it look even when compared to green.Of course, you can put additional red leds in series for the same voltage compared to other colors. So in large series strings the forward voltage is less of an issue.