See all the colors you can squeeze out of a Full Color LED

Here is a simple program to randomly see all the color combination you can draw out of a FULL Color LED from Radio Shack.

The Full color 5mm LED from RadioShack (276-0028) has 4 leads: (from the flat side of the LED body) pin 1 Red (-) pin 2 Positive Voltage pin 3 Blue (-) pin 4 Green (-)

To trigger the desired color you set the pin to ground; so- if you want red, you would have voltage on pin 2 and pin 1 to ground... Blue would be the same except you ground pin 3 and so forth.

On it's own, the LED can only display one color at a time. When you use the PWM of analogWrite() from a Arduino you can watch all the color combinations that you can make with the LED.

Note about operation. PWM (Pulse Width Modulation) causes the LED to see a variance in voltage between 0 (0) and 5 (255) volts on a pin. When the LED sees 0 volts on a pin, that color will be the brightest. If the pin see 5 volts (255) the color will no show.

Hook up a 5 volt supply from the Arduino. Add a resistor to Pin 2 of the LED (220 Ohms)

Add three wires from PWM pins from the Arduino. I used 2,3,4 on my Mega (use whatever you want). Then use the code to randomly generate colors on the LED.

I included serial output so you can monitor the RGB numbers as the LED changes.

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Pensive 3 weeks, 4 days ago

Just an clarifying note, PWM does not present varying voltages between 0 and 5v, it simply pulses either 0v or 5v. So at low dim levels you should expect a visible flicker. The voltage remains the same at all times. I'm sure this is what the OP meant, but it might confuse a noob :)