Picture your hands after you’ve just watched an amazing performance. An evening spent clapping has probably left them red, tired, and blazing with pain. That’s why I created a portable applause solution for the 21st-century human. With high-quality sound, speed control, and a custom laser-cut case, the Applause Machine will do your clapping for you.
To build it, I started with a pair of tongs from my kitchen. I attached a metal spring below the grippers, and put an oval-shaped DC motor between the arms. When the motor spins, it forces the tongs to open and close, creating a clapping motion. As for the machine’s hands, I wanted to find a pair that would create the most realistic clapping sound possible. So I bought four different types of plastic hands from a party-supply store. After some experimentation, I decided that hollow hands made of rigid plastic created the best noise. I fastened them to the tongs’ grippers with small bolts.
When it came to the machine’s power supply, I ran into trouble. The Applause Machine is controlled by an Arduino UNO: a tiny, inexpensive microcontroller that’s great at reading sensors and managing hardware like motors. But it has only a 5-volt output, and the DC motor required 12 volts to run. To solve this problem, I inserted a MOSFET transistor—which allows you to control a high voltage with a low one—between the Arduino and the motor.
Last but not least, I added a slider to the front of the machine to control the speed. It can gradually increase from a snarky slow clap to a breakneck 330 claps per minute. After testing, it was evident that the Applause Machine is set to make the torturous practice of applauding a relic of days gone by.
This article was originally published in the March/April 2016 issue of Popular Science, under the title “You Need an Applause Machine.”