Introduction: LED Snapper: Probably the Most Basic Piece of Test Equipment You Can Make

Allow me to introduce to you the LED Snapper. A simple, but massively useful piece of test equipment that you can build to help you debug your electronics projects. LED Snapper is an open source printed circuit board that allows you to easily add debugging and test LEDs to your projects. It is designed to snap into your breadboard (hence the name) quickly without any messing around with multiple LEDs and resistors. You can download and modify the Gerber files to have the PCB made for free.


  • LED Snapper PCB
  • 8 x 5 mm LEDs of the colour of your choice
  • 8 x 220 Ohm resistors
  • 9 pin Male pin header

Step 1: How to Build It

You'll need a soldering iron to fix the components to the board. Begin by soldering the resistors (220 Ohms each) first. Then solder the header pins. Next, insert LEDs of the colour of your choice and solder each in turn. The positive anode (the long leg) of the LED goes in the top hole on the PCB and the negative cathode goes in the bottom hole next to the resistor.

That's it! It should take you about twenty minutes to solder the components onto the board.

Step 2: How to Use It

Snap it into your breadboard. Connect up the GND pin to ground and then connect one, or more of the 8 pins connected to LEDs to say, the Arduino's pins or any other 5 volt chip, or circuit that you want to test. The LEDs will light up when they get a high signal from the Arduino, or greater than 1.2 volts if you are using some other circuit. Don't feed more than 5 volts into the LED Snapper's pins, or you may burn out the LEDs.

Simple, isn't it? I did say it was the most basic piece of test equipment that you can build. But, being able to see the state of the pins on the Arduino is sometimes essential when you want to get your circuits to work and LEDs are perfect for the job.

Step 3: How to Obtain the PCBs

There are 3 different boards to choose from. The first is shown above with the pin numbers increasing in order from left to right. A second board is nearly identical to this except the pin numbers decrease in order from left to right. This board is useful if you want to view a binary number output from the Arduino because the pins are in the right order to read binary numbers.

I have uploaded the Gerber files for the PCB to my GitHub repository. You can access the repository by clicking this link and download the files. Each board is identified with an image and the name of the Gerber files to download in the README.

I used JLCPCB to make my boards, but any PCB manufacturer that allows you to upload Gerber files and have the boards manufactured will do. There are plenty to choose from on the Internet. PCBWay is also another good choice of board manufacturer.