Introduction: Laser Sign

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Use some lasers to write on the wall!

You need:

8 laser leds (you can buy them for 4 euros here).

two-coil stepper motor

small mirror

arduino nano

4 power NPN transistors, 4 power PNP transistors, 8 1k resistors. Wires

support

Step 1: Build a Controller for the Stepper Motor

Build a dual H bridge, using the above schematics, which I obtained from here. (Thanks Kerry Wong!)

Step 2: Attach the Lasers to a Support and Wire Them to the Arduino

Connect 8 of the lasers to the arduino (1 i/o pin for each laser) and fix them to something solid (I used a scrap PCB).

Step 3: Paste a Mirror to the Motor

Step 4:

Mount everything on some support (I used an old ethernet switch).

Step 5: Write the Code.

Here is the code I used. At the very least you should assign the correct pins you used to connect the lasers and the hbridge.

Step 6: Done, Enjoy!

You can control it with an android phone using an OTG cable (you can build one yourself using the above schematics from here) and a serial terminal app (I’m using this one). Set the speed to 9600. Whatever you type in the app will be echoed on the wall.