How to Build a Laser-Activated Singing

Justin Bieber Cardboard Cutout By Matt Huang

Intro: Do you love or love to hate Justin Bieber? Are you a crafty person who takes pleasure

in zapping (cardboard) people with lasers? If you answered yes to any of these questions,

this project is for you! You will create a singing Justin Bieber that is activated with a laser

pointer.

Estimated Time Needed: 1-2 hours

Materials Needed:

Life-size Justin Bieber cutout

Beanie or Knit Cap

20 feet of Electrical Wire

2 resistive light sensors

Electrical Tape

Regular Tape

Laser pointer

Assorted Sizes of Cylindrical Cardboard

Tubes (or other craft materials to make a

necklace out of)

Pico Board and USB Cable

Computer

Tools Needed:

Wire stripper/cutter

Pliers

Scissors

First Steps: Programming in Scratch

1. Install Scratch on your computer. http://scratch.mit.edu/download

2. Open Scratch and create the following script:

NOTE: You will need to import a Justin Bieber song as an MP3 into Scratch. This

example uses the song “Baby”, denoted in the script as “Baby Final”.

Figure 1: Script for program in Scratch

Next Steps: Connect Light Sensors to Pico Board

3. We need to connect a light sensor to both resistance-A and resistance-B on the Pico

Board. Using the wire cutter, cut four 5-foot pieces of electrical wire.

4. Use the wire stripper to strip off .5” from the ends of each wire.

5. Take a light sensor and use the pliers to wrap a wire on each end of the sensor.

6. Use the electrical tape to secure the wires to the sensor.

7. Repeat steps 5-6 for the remaining sensor.

8. Using the alligator clamps, clamp the wires leading from the first light sensor to

resistance-A. Clamp the wires leading from the second light sensor to resistance-B.

Figure 2: Pico board with light sensors connected to resistance-A and resistance-B

We’re Nearly There: Upload Script to Pico Board

9. Plug the pico board into your computer via USB cable

10. Check that your pico board is registering with Scratch by going to the “Sensing” menu,

selecting “resistance-A” in the drop down menu for “sensor value”, and checking the

check box.

Figure 3: Check sensor values

11. Repeat step 10 by selecting “resistance-B” instead of A.

12. Verify that your pico board is registering by looking at the resistance-A and resistance-

B values in the top right of the Scratch window. The values should be fluctuating

mildly. Depending on the level of ambient light in your environment, the values can be

anywhere in the range of 10-60.

13. Press the green flag button in the top right of the Scratch window. Your script should

now be uploaded to the pico board. Test to see if it’s working by shining the laser

pointer at the resistance-A light sensor. The Justin Bieber song you selected should

start playing. Now shine the laser pointer at the resistance-B light sensor. You should

hear a loud “OWWW!!” and the song should stop playing. If everything is working,

press the red stop button next to the green flag to stop the program.

And now for the crafty part: Attaching sensors to Justin Bieber

14. Create a necklace using the cardboard tubes. Feel free to improvise and utilize your

creativity in this step-the necklace can be made out of a variety of additional materials.

It’s main function is to contain the light sensor that will trigger the song.

15. Hang the necklace on the Justin Bieber cutout.

16. Loop the resistance-A light sensor into the necklace so that the sensor is positioned in

the middle of the cutout’s stomach. Wrap the electric wire behind the necklace and

snake it over the cutout’s shoulders so that the wire hangs behind the cutout.

17. Position the resistance-B light sensor directly in front of one of the cutout’s eyes using

tape. Snake the electric wire over the cutout’s head so the wire hangs behind the

cutout.

18. Place the beanie on the cutout’s head to hide the electrical wire connecting the light

sensor on Justin Bieber’s eye.

19. Test out your creation!! Make sure all the wires are connected to the pico board, hit

the green flag button, and have fun as you zap Justin Bieber with lasers! This project

makes for great amusement at a party.

Figure 4: The finished project

Troubleshooting

If Sensor Values don’t fluctuate and are stuck at 0 or 100: Try disconnecting your pico

board and restarting your computer. After reopening Scratch, reconnect the pico

board.

If MP3 file doesn’t import: Try using a different MP3 file or use the Record New Sound

button to record the MP3 playing in an audio player (like iTunes) on your computer.

Need help? Have questions? Contact Matt Huang on Twitter: @mtthg