Hacking Holiday LED Light Strings With Makey Makey



Less than 1 hr

About: Computers are going bananas! Use #makeymakey to practice invention literacy and connect the world to your computer.

Learn to hack LED light strings to light up only on certain key presses. This is a hack that uses Makey Makey in a completely unconventional way! It's an advanced guide for makers who want to try something a little wacky!


Makey Makey Classic, Battery-powered LED light strings, Conductive Tape, Wire Strippers, Paper Craft Supplies

Step 1: Project Overview

In this guide, you'll be using Makey Makey in a way you are not really supposed to use it! So just know that this method does not fall under support and you are following this Makey Makey guide at your own risk!

As Harry Potter via J.K. Rowling would say, "I solemnly swear I am up to no good."

This hack uses Makey Makey to light five different strings of LED light. However, the hack that allows you to do this is completely unconventional and you have to use your Makey Makey in a way different way.

Therefore, this is an advanced guide, so if you are new to Makey Makey, please try a few other guides and make sure you understand how to code and create with Makey Makey before trying this hack.

Watch the video below to see the lights in action!

To begin, you'll need to find some battery-powered LED string lights at your local craft store that only require 2-3 double AA batteries. (Similar to Picture 2)

The first step to hacking LED string lights is to cut off the battery pack from the light string. Make sure when you cut the battery pack off, you leave at least 2-3 inches of wire connected to the battery pack, so you can use this component for another project. (Picture 3)

Educator Tip:

A Makey Makey can supply enough voltage (about 5V) to control battery-powered holiday lights. The LEDs from a big strand of "plug in the wall holiday lights" can probably be hacked individually, but for this hack it is easier to hack a string of battery-powered lights. (Most battery-powered LED string lights require 2 -3 double AA batteries, so that means these lights can be powered by the 5V supplied from the KEY OUT pin on the Makey Makey.)

You'll make switches to control your lights, I made mine look like a tree with colorful paper bulbs as my switches. (Picture 1) I used four different types of battery powered lights, but I'm only including a picture of one very cheap set I found at Michaels! (Picture 2) The first step to hacking string lights is to cut off the battery pack from the light string. Make sure when you cut the battery pack off, you leave at least 2-3 inches of wire connected to the battery pack, so you can re-use this component for another project in the future. (Picture 3)

Step 2: Hack Battery Powered LED String Lights

Once you've cut off the battery pack, you'll want to separate the positive and negative lead. In most cases, you can clip with scissors. Be careful not to cut into the wiring. (Picture 1 and 2)

Use wire strippers to strip about 1/2" of the insulation off of each wire to expose the inner wiring. (Picture 3 and 4)

Repeat this for each strand of LED lights you want to hack!

Educator Tip:

If your students haven't used wire strippers, yet, this is a good time to teach them how! Wire strippers come in handy when inventing your own switches for Makey Makey.

Step 3: Determine Polarity

Determine the polarity of your lights, by plugging one exposed wire to KEY OUT (on the back of your Makey Makey) and the other wire to EARTH. (Picture 1 and 2)

Use your hand to hold EARTH and press a key press to see if you have wired your lights correctly. If they light up, AWESOME! Move on to your next light string. If they do not light up, switch the alligator clips and try again.

Since you are going to wire multiple LEDS, try to use gray or black for the EARTH or grounding wire. It will help you when programming your LEDS and in the next step when we change the wiring for a specific key press instead of using the KEY OUT pin.

In my image, I have a green alligator clip for KEY OUT and a gray alligator clip for EARTH. If you look back at step one, you'll see I actually matched the paper switch color with the alligator clip AND the color of my paper trees! It helps to color code when you have an extended project like this, but color coding is not a requirement. ;)

When you have all of your LED light strips lighting up on any key press using the KEY OUT function on your Makey Makey, then you are ready for the next step!

Step 4: Create a Scratch Piano

Create a five note (or more!) piano in Scratch to play your holiday jingle.

In Picture 1 you can see my 5 note scale I used to play Jingle Bells. This is pretty simple coding! Just create a program for each key press to play a different note.

Step 5: Test the Hack!

Decorate an object with your LED lights and get ready for the hack by watching this video.

Before creating paper switches, I tested the hack by placing five conductive tape traces on a piece of paper like a paper piano. Then I labeled each tape trace with the key press I'm using on the Makey Makey. Make sure to plug an alligator clip from each tape trace to a key press on your Makey Makey.

To light different strands of lights with different key presses (instead of every light going off with every key press), you are going to have to wire this in a completely different way than you would normally use a Makey Makey. Previously, you used KEY OUT to light your Makey Makey, but now you are going to move each positive wire from KEY OUT to a specific key press.

Leave the alligator clips on your LED string lights, but move the positive alligator clip from KEY OUT on the Makey Makey to the key press you would like to control each light. The LED strings for each tree need to be plugged to a different key press and an EARTH pin to ground the lights.

The positive wire on each tree is plugged to a specific key press and the negative lead is plugged to an EARTH input on the bottom row. Here is how I wired mine:

  • The top of the tree is plugged to SPACE and EARTH
  • The white tree is plugged to LEFT Arrow and EARTH
  • The green tree is plugged to UP Arrow and EARTH
  • The pink tree is plugged to RIGHT Arrow and EARTH
  • The orange tree is plugged to DOWN Arrow and EARTH

Now normally, you would use an alligator clip from EARTH to touch each tape and all of your trees would light up. Plus normally, you can use your hands or any conductive item. But to control each light individually, we are going to use the KEY OUT pin as a way to trigger the lights and internally ground each input. Since this sends the power out, you can not use your hands to trigger the effect. You'll have to use the alligator clip and conductive tape as this allows the hack to work!

To use KEY OUT, push a white hook up wire into the KEY OUT pin and clip an alligator clip to the wire. Now you can test your light strands by tapping the alligator clip to each key in your paper piano.

Does it work? Did you get each strand to light up separately?

If you are having trouble, watch this video.

Note: This is a lot of alligator clips on a Makey Makey, but I plugged into the front and the back. In fact, sometimes I just clipped onto the alligator clip already plugged onto the key press! (See picture 2.)

Step 6: Create Paper Switches

Using conductive tape, you will create switches as tapping with your hands will not work with this hack. To create a switch you need two conductive sides that only touch for a moment when you press on the top of the switch. For my switches, I put a piece of conductive tape on a paper bulb shape making sure to run the tape ran from the underside of the bulb to the top. (Picture 1 and 2). This helps my paper "bulbs" look like bulbs, but also allows me to connect my alligator clips to my bulb and the cardboard tree just by clipping it on with an alligator clip like in picture 3. Each bulb is wired to a key press, so when I press on a bulb, it will light the corresponding tree. To do this, I matched each bulb alligator clip to the same key press as the tree of that color. Each bulb needs to go to a key press so you can trigger the sound and the lights! (I moved them from my paper piano in the previous step)

Here is how I set mine up:

  • Yellow to SPACE
  • White snowflake to LEFT
  • Green to UP
  • Pink to RIGHT
  • Orange to DOWN

Normally, at this point, you would create an EARTH to function as the ground of your switch. That's how I ran the gray conductive tape on my cardboard tree. However, instead of plugging to EARTH, I plugged this tape trace to KEY OUT.

Now when I close the circuit by pressing the switch, I actually supply power to each LED light strand individually.

Step 7: Play!

Now you are ready to control lights and play your favorite jingle!



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