- 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.
Step #6: Transistor to Ground
Connect the emitter of all three transistors to ground.
- Connect your Arduino to your computer (running Windows, OSX, Linux).
- Open the Arduino program and upload the Arduino code within the following images.
Step #10: Arduino Serial Monitor Testing
- 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
Step #13: LED all on or off
All RGB cathodes on or off.
Yes, that is correct. While testing for this guide, I used the 2N2222 transistor, but during the process of taking the photos for the guide, I accidentally used the 2N3904 transistor with the same application as the 2N2222 transistor, and oddly the circuit worked, but on the safe side, yes, the users should have precautions of what and how the application of this guide is used. I will set that as a note or warning, thanks for the heads up.
I read about transistors before but what do we need them in here for, I was wondering if anybody could educate me on that, I’m just curious for understanding and knowledge sake