The current flowing into the base of the transistor is what causes the transistor to close the circuit.Īt this point we have a discussion noting the similarities and differences between a transistor, push-button, and switch. The current must flow into the LED through the Anode lead. Add the LED so the Anode is on the same connection as the resistor. Place a small breadboard onto the work area. Switchesįor this project, we will need a breadboard, LED, resistors, button, and transistor. The first project will help us compare how the second project with two power sources differs and the advantages of having two power sources. Our first project will have one power source. One power source activates the base and another source powers a component. We typically have two power sources for a circuit with transistors. The current stimulates the base to allow the flow of current across the collector and emitter. This transistor has a negatively charged layer sandwiched between two positively charged semiconductors.įor the transistor to work as a switch the base must receive electric current. This is the transistor we will use in our lesson. This positively charged layer is sandwiched between two negatively charged layers. The center material is depleted of electrons. Each end of the transistor is made of a semiconductor material that is saturated with electrons. The NPN transistor is the most popular and common. The difference in the type of transistor depends on how it is manufactured. Each transistor is referred to as either a PNP or NPN transistor. The location of the emitter and collector depend on the type of transistor being used. You will see an image of this transistor later in the lesson. The leads on either side are called the Collector and Emitter. In this lesson, we will learn to use the transistor as a switch. Transistors have made fast and small computers possible. Transistors and LEDs have revolutionized our modern world.

Transistor as a switch download