Arduino + 4 pin 5mm Full-Color LED

This circuit uses an Arduino UNO but it still works on an Arduino MEGA 2560.

In this project we only use one 5mm LED, but since the LED has four pins, I used three LED symbols in place of the four-pin LED. The three cathodes of the LEDs in the schematic are the three cathodes on the Full-Color 5mm LED. The three anodes of the LEDs are the one anode on the Full-Color 5mm LED.

Remember, the longest pin of the LED is the anode, the other three short pins are the cathodes (RGB)

Also, while the flat side of the transistor is facing you, the left pin is the collector, the middle is the base, and the right pin is the emitter.

The photo notes the 2N2222 transistor. For the 2N3904 and 2N4401, the Collector and Emitter are switched.

Connect the LED to the breadboard.

Connect the anode of the LED to the other half of the breadboard.

Connect the cathode (frist pin) to the other side of the breadboard.

Connect the collector of one transistor to the first cathode of the LED.

Connect the other transistors as shown in the image. Connect the collector of the second transistor to the second cathode of the LED.

Connect the collector of the third transistor to the third cathode of the LED.

I’m using the 2N2222 transistor, so in my case the transistor faces my direction. If the 2N3904 or 2N4401 transistor are used, the transistor will face the opposite direction.

Connect one resistor to the base of the third transistor.

Connect the second resistor to the base of the second transistor.

Connect the third resistor to the base of the first transistor.

Connect the emitter of all three transistors to ground.

Connect the resistor from the third transistor to pin 9 on the Arduino.

Connect the resistor from the second transistor to pin 10 on the Arduino.

Connect the resistor from the first transistor to pin 11 on the Arduino.

Connect the anode of the LED to pin 12 on the Arduino.

Connect ground from the Arduino to the ground strip of the breadboard.

Connect your Arduino to your computer (running Windows, OSX, Linux).

Open the Arduino program and upload the Arduino code within the following images.

After uploading the code, open the serial monitor and input a character from 1 – 8.

1 = RED, 2 = GREEN, 3 = BLUE

The LED only has three pins for RGB (Red, Green, Blue), but turning on more then one pin creates diverse colors.

4 = PURPLE, 5 = AQUA, 6 = ORANGE, 7 = BRIGHT WHITISH PURPLE

8 = OFF

Normal RGB light settings.

Other RGB settings. RB, GB, or RG.

All RGB cathodes on or off.