This project adds a 2N2222A NPN transistor to the Arduino Blink project. I set VCCA to 5V but you can use any voltage within the spec of the 2N2222A. This is just a switch controlled by pin 6 powering the base to engage the transistor. On the collector side I have 5V – LED – and 220Ω resistor. The emitter side goes to ground. When the base energizes the 2N2222A, the Collector load goes to the emitter ground completing the circuit.
