Learn Electronics: The Transistor

The transistor is a simple component that you can use to build a lot of fun projects. In this hands-on course, you’ll learn how transistors work so that you can use them in your next circuit.

The transistor is the most important component in electronics. It makes it possible to add if-this-then-that logic into your circuits. For example:

  • If it's dark outside, turn on the lamp.
  • If it's warm inside, turn off the heater.
  • If the output of the chip is high, turn on a motor.

Almost all Integrated Circuits (ICs) are made up of transistors on a chip, connected in a specific way to create the function your IC provides. So even if you're not using transistors directly, you're enjoying their benefits.

In this course, you're going to master using the transistor as a switch. You'll also get an introduction to how you can use it as an amplifier with links to more resources for those who want to dive even deeper into that subject.

The focus of this course will be on the two most common transistor types; BJT and MOSFET.


To follow along with this course, you should have a good understanding of how currents flow and voltages behave in a circuit.

We recommend going through the following courses prior to this:

Components Needed

  • 9V Battery
  • 9V Battery Clip
  • Breadboard
  • Pushbutton
  • NPN Transistor (Most NPNs will work. We used BC547)
  • nMOS Transistor (Most nMOS transistors will work. We used IPP055N03L)
  • Schmitt-trigger Inverter (74C14 or CD40106)
  • 100 µF Capacitor
  • 6 x Red LED
  • 6 x 470 Ω Resistor
  • 2 x 1 kΩ Resistor
  • 2 x 10 kΩ Resistor

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