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Howto choose RGB leds ? Answered

Hi, I need to buy some nice looking RGB leds. What I want is a led that can be turned pink, yellow, green, cyan, magenta... whatever. What I have received are leds that project three different beams, one red, one red, one blue, making three different colored spot, but do not look like one homogenly colored led. So my question is : -How to now from the spec if the led will look nice or will look like the one I already have ? -Where to buy 25-50 nive rgb leds for a fair price ? Regards, tReg.



9 years ago

Thanks you kelseymh and kiteman.

Just to make my problem more clear : I *know* that RGB leds are three die in one led, and I know how to control them (actually I'm using a TLC5940 with a PIC18F4550 connected via USB to my PC).

So, maybe the answer is "if you diffuse the led" : do you mean that I should try something like using sand paper on the led to make it "frosted" so the three colors get correctly mixed (so I can se one homogenous color instead of three different spots ?)

When you looks at this picture : http://www.semifluid.com/?p=12 , you se that he manages o have pink, cyan, yellow and white color using RGB leds. When I try to do this with the leds I bought, I get something like the one on this page : http://cgi.ebay.com/10PCS-12V-DC-5mm-LED-Wired-Fast-Flashing-MultiColor-RGB_W0QQitemZ150312715921QQcmdZViewItemQQptZBI_Electronic_Components?hash=item150312715921&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318 , which is NOT what I am looking for.

On the picture on the first page (the "good" one), there seems to be no diffuser, unpolished of the leds, or anything. What I'd like is to purchase leds like this ones :)


Kiteman gave the short answer. Here's the longer one. You need three separate power supplies for each of the three component LEDs. Each supply needs to support pulse-width modulation to vary the (apparent, due to human POV) intensity. By adjusting the intensities and using a diffuser, you can construct any color you want.

If you're really ambitious, you could use something like an Arduino to take RGB color codes (3-byte numbers) as input and drive the power supplies for the LED. It's do-it yourself Diamondvision!

"RGB" LEDs are just that - Red, Green and Blue LEDs in one unit. The other colours are made by controlling which ones are one or off. If you diffuse the LED, the colours will mix and show up differently.