From the Toolbox: LEDs
LEDs (Light-Emitting Diodes) are all around us; in our cars, electronic devices, home appliances, and other essential products for everyday life. They are versatile, relatively easy to integrate, and come in a variety of forms. To provide you with a little history lesson on LEDs, the baseline technology was first discovered by British experimenter Henry Joseph Round in 1907. However, the first visible-light LED would not have been invented until 1962 by General Electric engineer Nick Holonyack.
What’s Inside an LED?
LEDs are made up of several semiconductor materials, depending on the LED. These include:
Indium gallium nitride – Blue, green, and ultraviolet high brightness LEDs
Aluminum gallium arsenide – Red and infrared LEDs
Gallium phosphide – Yellow and green LEDs
Aluminum gallium indium phosphide – Yellow, orange, and red LEDs
If you were to look inside a standard LED lightbulb, you would find the following components:
Driver – A self-contained power supply that regulates the LED output.
Heat sink – Keeps damaging heat away from the main light source and distributes that heat into the air.
The typical 2-pin LED diode, which is used for prototyping, has two main wires that provide power: The anode (positive) wire and the cathode (negative) wire. The electrical current runs one way, from anode to cathode.
Types of LEDs
There are four main types of LEDs used in electronics prototyping, and whether you choose to use each type depends on the application. Here is a brief description for each type:
Through-Hole LEDs
Best for applications—such as automotive interiors—that require backlighting. They come in a wide range of sizes, from 3mm to 10mm, as well as a rainbow of colors.
RGB LEDs
Most used by designers, RGB LEDs contain three LEDs in one: red, green, and blue. The beauty of this LED is how you can produce additional colors. For example, say you want to produce a bright white light, you can set the LED to the highest intensity.
Surface Mount LED
Surface Mount LEDs—also known as SMD LEDs—are a seamless option for prototyping because they are wireless. They can be soldered directly to Printed Circuit Boards and are especially great for providing portable devices with lighting.
High-Power LEDs
High-power LEDs are powerful LEDs with high brightness. They come in two forms, as a Bare Emitter or mounted on a metal PCB, and are commonly used in automotive headlamps and flashlights.
Prototyping with LEDs
There are many ways to use LEDs in a project. No matter if it is light-up décor or a wearable, there are certain methods for how LEDs should be integrated. In most cases, you will need to attach a resistor to LEDs (usually if it is a Through-Hole) and then solder them all together. Other times, you will need to solder directly to a microcontroller. It all depends on the product you are working on and its needs.
If you are working with our Single Backlit Button, the integration will be different than the typical LED. The LED in the backlit button is embedded in a flexible e-textile. This component can either be soldered to headers or adhered to surfaces via the sticky backing. You may hear ‘e-textile’ and think it’s OK to sew this component. However, we advise against this.
Applications
One of the great things about LEDs is how truly versatile they are. The potential applications for LEDs are endless, and there are little to no bounds for experimentation. In large industries such as automotive and home appliances, they can be used in car headliners and microwaves. They can also be used in smaller-scale projects like home décor and fashion accessories. LEDs have been used in some cool Loomia projects, as well! The Convertible Solar Safety bag created by the talented folks at Amped Atelier utilizes two LED strips to create safety lighting on the bag, and a Single Backlit Button to control the LED functionality.
Here are some additional projects from Sparkfun to trigger some inspiration:
LEDs have come a long way since 1962, and the technology continues to evolve. There are so many different variations available on the market today for prototyping, it’s hard to keep track of: LEDs mounted on PCBs, LED strips, LED chains, LED sticks, and the list goes on. You would be pleased to know that LEDs are also highly energy-efficient and last longer than halogen and fluorescent lighting. So, the next time you go shopping for bulbs, keep this in mind. Should you want more in-depth information on LEDs, we highly recommend checking out the Sparkfun blog. There you will find a whole slew of articles explaining in detail what they are, how they work, and how they can be used.