Below is a diagram of how this works. I used a 2N4401 NPN transistor that “turns on” when the gate goes high or positive. This essentially allows it to switch the negative or ground leg of the circuit. I did this because the Arduino can’t turn a digital IO line to ground- just 0v or 5v. Continue reading “Using a Transistor to Control an LED or anything”
Below is the breadboard circuit diagram. It’s pretty final. I hope to clean it up a bit when the project is final.
The major additions in this rev is that I’m using transistors against the Arduino digital outs to control the AC relays and a corresponding LED indicator. The on/off switches in those circuits provide a bypass to turn on the AC switches if necessary.