Makey Makey inventions are designed as computer inputs that connect to your computer through USB. You create buttons and switches to control your favorite games, make music, or interact with apps. However, you may have found yourself wanting a simple output—like a light—to show that a switch has been pressed, or maybe you just want to add a bit of flair to your project by making something light up when you press a key.
hack: using leds with makey makey
Introduction
Hack Details
Time: 30 Minutes
Difficulty: Advanced
Adult Supervision: Required
Tool Requirements: Hand Tools
Modification Warning
This hack could permanently modify your Retro Joystick! Please keep that in mind as you work.
Tools and Materials
We recommend completing this hack under adult supervision. This is considered an “advanced” hack that requires tools and materials not included in the standard Makey Makey kit. Read this guide carefully as we specify which components and tools to use, and note important safety precautions to prevent damage.
This hack can be completed without the Optional Materials, but they do make things easier.
We strongly recommend having an adult present to assist with the use of the craft knife and/or the drill recommended in this hack. Proper safety instructions for your specific tools should be followed!
Required Tools
- Scissors
- Wire Strippers
- Needle Nose Pliers
- Sharp Pencil or X-acto knife
- Hot Glue / Hot Glue Gun
Required Materials
- Completed Retro Joystick with Makey Makey
- 5mm LEDs (Any color)
- Conductive Fabric Tape
- Alligator Clips
- Connector Wires OR Ruggedized Connector wires
Optional Materials
- 3/16" Drill Bit
- Drill
LEDs on Your Makey Makey
The Makey Makey includes several small LEDs built right onto the board. You’ll find a red one on the back that serves as the power LED—it turns on when your Makey Makey is plugged in.
There are also several green LEDs on both the front and back of the board. These light up whenever you complete a circuit between EARTH and the keypress associated with that LED. These are the same LEDs that flash in a cool pattern when you first connect your Makey Makey! They provide helpful visual feedback to confirm that you’ve completed a circuit.
You’ll also find green LEDs on the back of the board that indicate whether you’re using a Mouse or Keyboard input. There are two of each—one above each of the keyboard or mouse headers.
Finally, there are red LEDs near the output header that show whether the KEY_OUT (keyboard output) or MS_OUT (mouse output) pins are on or off.
The Makey Makey Output Header
On the back of the Makey Makey, you’ll see the electronic components that make the board function. This is also where you’ll find headers that allow you to access additional keypress and mouse controls.
The header we’ll focus on in this hack is the OUTPUT Header, located at the top center of the board.
There are five pins on this header (from right to left): 5V (5 Volts), GND (Ground/EARTH), GND (Ground/EARTH), MS_OUT (Mouse Output), and KEY_OUT (Keyboard Output). In this hack, we’ll focus on four of the five pins and leave the 5V pin alone!
This header is different from the others because it’s the only place on the Makey Makey that provides outputs—everything else is input. On this header, there are only two outputs: KEY_OUT and MS_OUT. Each of these outputs turns “on” when you trigger either a keyboard keypress (KEY_OUT) or a mouse function (MS_OUT). Otherwise, those outputs remain “off.”
In this guide, we’ll explore how to creatively use these outputs with LEDs to add some blinky awesomeness to your inventions!
Pro Tip: It is easier to design and cut out the shape of your pad first, then cut it in half!
About LEDs
Light Emitting Diodes (LEDs) are everywhere in our modern world! The lights in your room, the display you’re reading this on, and even your microwave display all use LEDs. Before adding LEDs to your Makey Makey project, let’s explore what makes them so special and how their unique properties can work to your advantage.
LEDs were invented in 1927 by Russian inventor Oleg Losev, but they weren’t commercially available until the early 1960s. Early versions emitted red light for displays like alarm clocks or invisible infrared light for remote controls.
Anatomy of an LED
LEDs may look like tiny light bulbs, but they behave differently. Let’s take a closer look at their parts and how they work.
Each LED has two legs—one longer than the other. LEDs are polarized semiconductors, meaning they only allow current to flow in one direction. The longer leg is the Anode (positive +), and the shorter leg is the Cathode (negative –).
If you connect the anode to a voltage source and the cathode to ground (EARTH), the LED will light up. If you reverse the connection, it won’t.
When using LEDs with Makey Makey, connect one of the output pins (KEY_OUT or MS_OUT) to the Anode, and connect GND (Ground) to the Cathode.
You can make a simple version of this circuit by plugging an LED directly into the Makey Makey:
Long leg (Anode) → MS_OUT
Short leg (Cathode) → GND
Touch CLICK and EARTH, and the LED will light up! If it doesn’t, remove the LED and check your connections.
Preparing LEDs for Makey Makey
You now have a bit of knowledge and experience with LEDs, but let’s level things up and look at using LEDs in an invention! One challenge when working with LEDs is attaching alligator clips to their thin legs. The clips can easily slip off or touch each other, causing a short circuit.
To fix this, sse needle-nose pliers to twist each leg into a small curl for a better grip.
This leaves both legs curled and easier to alligator clip to. You can even bend them out away from one another to give the clips some room!
Pro Tip: After curling the legs, it can be hard to tell which one is which. Use a fine-tip marker to label the Anode, or look for the flat edge near the Cathode as a visual cue.
Connecting LEDs to Makey Makey
The other challenge is connecting the clips to the Makey Makey header, which isn’t alligator clip–friendly. Use the white wires from your Makey Makey kit.
Plug one end of a wire into the header pin and clip the other to the legs of your LED.
MS_OUT → White Wire → Alligator Clip → Anode
GND → White Wire → Alligator Clip → Cathode
Test your circuit by connecting CLICK and EARTH.
If your LED doesn’t light up:
- Make sure the clips or legs aren’t touching.
- Double-check your wiring (long leg → MS_OUT).
- Ensure wire ends are securely plugged into the header.
- Try another LED.
⚠️ A Word of Warning ⚠️
Never use the 5V pin on your Makey Makey with LEDs—it can damage your LEDs or your board! Like many electronic components, LEDs are fragile and can be damaged if connected incorrectly or exposed to too much current.
That’s why we avoid using the 5V pin—it provides too much current and will burn out the LED (sometimes with a smell of burning plastic). Once that happens, the LED won’t work again!
How Many LEDs Can I Add?
Now that you know how LEDs work, it’s time to integrate them into your own inventions!
The first question you may ask is: “How many LEDs can I add?”
LEDs require current to light up, and there’s a limit to how much you can draw from the MS_OUT and KEY_OUT pins.
The answer is "it depends", but the quick answer you are looking for is "two"—you can connect up to two red LEDs in series (one after another) before they stop lighting properly. This number may vary depending on LED color, since each color has different voltage requirements. To expand your lighting, connect one string of LEDs to each output pin for more effects!
How Do I Mount Them to My Invention?
Mounting LEDs can be tricky and may require tools as well as some help from an adult!
If your project is made of cardboard (like the Keytar), you can punch holes with a sharp pencil or bamboo skewer. Carefully press through the cardboard, checking the fit as you go. A 5mm LED fits snugly in a hole just smaller than the thickness of a pencil.
Once it fits tightly, use a dab of hot glue or white glue to secure it. Avoid super glue—it’s hard to remove later.
For materials like wood or plastic, use a 3/16” drill bit with help from an adult. Drill slowly, test-fit the LED, and slightly widen the hole for a perfect press fit from the back / inside of the material. This method may not even need glue if the fit is snug enough.
How Do I Wire LED in My Invention?
Mounting LEDs is one thing; wiring them is another! If your project is enclosed (like the Retro Joystick), you can hide the wires and alligator clips you have been using easily. For more open projects (like the Keytar), conductive fabric tape works perfectly.
For enclosed projects where wires are easy to hide or conductive fabric tape just won't work, you can curl the legs of the LED and just use alligator clips! This is our preferred method with the Retro Joystick!
Mount the LEDs where you want them (noting the anode and cathode) and bend the legs flat. Then, use strips of conductive fabric tape to run the circuits as close to the Makey Makey as possible. Your goal is to get within the distance that a white connector wire can span!
With the conductive tape down, insert one end of a connector wire in the the Makey Makey KEY_OUT pin on the OUTPUT header. Gently, but firmly press it into the header, it should stay in with a snug fit. Now, bend the wire in the direction of the conductive tape connected to the anode (long leg) of the LED. Repeat the process for another wire connected to a GND pin on the back of the Makey Makey to the cathode of the LED circuit.
Cut a short piece of conductive fabric tape (1/2") for each wire. Bend the white connector wire so that its bare end falls on top of the circuit it should connect to and tape it down with the short piece of conductive fabric tape. Be sure to press down on the tape to make sure it seats well and connects the circuits to each wire. Test the circuit by connecting SPACE and EARTH... your LED should light up!
Tips for success:
- Draw a circuit diagram and test with alligator clips before using tape.
- Place a small piece of tape under each LED leg, then press another strip on top to sandwich it securely.
- Avoid overlapping tape lines! If you must cross them, cover one with masking tape before placing the next strip on top.
Conclusion
LEDs are a fun way to add visual feedback to your Makey Makey projects. They can be tricky at first, but with careful testing, patience, and these tips, your invention will be blinking and glowing in no time!
Troubleshooting Tips
- LED not lighting up? Check all of your connection points... alligator clips to LED, alligator clips to tape or wire. It is easy for something to come lose
- Still no light? Make sure that the long leg of the LED is connected to the output pin (KEY_OUT or MS_OUT) and the short leg is to GND.
- Nothing! Try another LED... you may be trying to use one that is burned out. When all else fails, test it by connecting it directly to the Makey Makey like in the start of this guide.
Show us how YOU hacked or modified your Invention Launchpad creation! Tag #MakeyMakeyLaunchpad and join our global community of inventors.