Lesson 3— Electronics for kids — What is a transistor?

Transistors

This story is part of a series. See this starting page for links to other lessons.

In this lesson we will learn about transistors and how they can be used as a switch.

Please see previous posts for components we have already used in the past. The only new component for this lesson is a transistor. This is arguably one of the most important components. You can explain to the child that their favorite tablet/TV etc has a microprocessor that contains billions of such transistors. They are small like germs!

This component has 3 pins and you will need to it in 3 different numbered slots on the breadboard. These are called the collector, base and emitter. Instead of physically turning a switch on or off, in this case sending electricity to the base turns it on and closes the circuit between the collector and the emitter.

A transistor with a collector, emitter and base

I have a NPN transistor and circuits are based on that. If you have a different kind search for needed modifications.

Have the child explore the new component then try to connect as shown. Help them by pointing to the numbers on the breadboard to connect wires/components.

Breadboard visual for circuit to use a transistor as a switch

Circuit diagram for using a transistor as a switch

Electricity flows through through the resistor on the top, through the LED and into the collector pin. At this point since we are not sending power to the base the switch is off so the light is not on.

Transistor with open circuit

Upon pressing the switch electricity flows to the base pin. This closes the circuit and electricity now flows from the collector to the emitter.

Transistor with closed circuit

This story is part of a series. See this starting page for links to other lessons.