I've spent nearly a week trying to figure out how to use them. I'm not talking about anything fancy, I just want to use one as a switch. In this learning experiment I want to have a battery going to a led, with a transistor controlling whether its on or off. I intend to have another power source going to a button which then goes to the transistor to turn the transistor on or off. Here's the part that I can't understand. Transistors have 3 pins. That just fries my brain. If transistors were a 4 pin component, it would be easy to comprehend. + and - of the circuit to be turned on and off by the transistor would connect to the 2 pins on one side, while the circuit turning the transistor itself on and off would connect to the other 2 pins. But that's obviously not how it works, since they have 3 pins. Everywhere I try to read about them loves to talk about the fact that they can be used as switches or can be used to amplify current, but I can't find anywhere telling about how to actually use them in a circuit.