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Dear IanP
the link you pointed does not have a RGY tricolour led , it have an RGB led.
But that is not my requirement.
any way thanks for your time..........
A red-green bicolor LED really is a tri color LED. When both the red and green are turned on simultaneously, you see yellow. It isn't necessary to manufacture a three special tri color device to do the job, so most manufacturers don't bother.
The three lead LED that displays the three colors does so by having the green emitting chip in series with the red emitting chip, and the common lead between the two diodes. When the common current flows in one direction, the color is green. When the current flows in the opposite direction, the color is red. Finally, when both chips are powered you see yellow. Remember that the light primary colors are not the same as pigment primary colors. In the world of light, colors are subtractive - RED+GREEN=YELLOW. You can even use PWM to control the visible hue. An example of a three lead LED that will produce red yellow and green can be seen at:
**broken link removed**
If you experiment with any bi color red/green LED, you will be able to produce yellow in addition to red and green when you power both red and green simultaneously.
If you really need three separate chips, you'll have to go with a device that mounts three discrete dies on a neutral substrate. An example of such a product can be seen at: http://capacitors.electronic.com.tw/smt-led/tri-color-led-lamp.htm
Look closely at the data sheet and you will find one with the three colors you seek.
No, it's not really a tri-color LED, it relies on persistence of vision to produce the sensation of yellow, it does not (as far as I know) produce yellow light as saturated as a true yellow LED.
One could design traffic lights using such LEDs too, and it would work for anyone who can recognise standard traffic signal colours.
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