Light-Emitting Diodes (LED)

A Light-Emitting Diode (LED) is a small component that lights up when there is current flowing through it. It’s used in light bulbs, displays, lighting decorations, and much more. In electronics, it’s often used for showing the state (is the gadget turned on?).

You can see the light-emitting diode everywhere! In laptops, on mobile phones, on cameras, on toys, in our car +++.

It’s a type of diode, so it only works when you connect it with its anode towards your battery’s plus terminal.

Chances are you will be working with LEDs a lot when you start learning electronics. They are cheap and simple to use, and it’s a great way to check if your circuit is working properly or not.

Do you want to adjust the brightness of your Light-Emitting Diode (LED)? If we break it down to the most basic, there are two ways to change the brightness of an LED:

• Changing the resistance value.
• Turning it on and off fast (Using PWM).

Below I’ll explain the two options and show you circuits you can build.

I got this question from Awaji about the light-emitting diode (LED):

[Awaji]: How can I know the LED voltage and the current ratings of an LED? Also, how is the resistor of an LED chosen? Thanks

[Oyvind]:

Here are three different ways to find the LED voltage and current:

1. The easiest way is to look it up in the datasheet, or the store where you bought it. Look for LED forward voltage and the Test Current.
2. You could find the LED voltage by using a multimeter with a diode function.
3. You could connect a battery to the LED and a potentiometer. Start with high resistance on the potentiometer and gradually decrease it until you have a nice brightness. Then measure the voltage over the LED, and measure the current going through the circuit.