Vernier Software and Technology
Vernier Software & Technology
Arduino and Vernier Sensors

Pendulum Driver

The Pendulum Driver sketch uses a photogate, a Digital Control Unit (DCU), and an electromagnet to keep a pendulum with a metal bob swinging forever. Set up a bifilar (i.e., two string) pendulum so it swings in a plane. The pendulum bob needs to be made of iron or steel. Connect the DCU to the Digital 2 port and connect an electromagnet wired between the first output of the DCU and the DCU ground. Position the electromagnet right below the bob at the bottom of the swing. Place a photogate, connected to the Digital 1 port, slightly to one side of the electromagnet so that the pendulum bob blocks the photogate as it swings down and approaches the electromagnet.

Pull the pendulum bob up behind the photogate, start the sketch and release the bob. The sketch will turn on the current to the electromagnet as soon as the bob blocks the photogate. This will cause the bob to be pulled downward and increase its speed slightly. The sketch is written so that the next time the bob blocks the photogate, the DCU does nothing. (If it did, it would be slowing down the pendulum bob.) Basically, every time the pendulum bob is swinging down toward the electromagnet, the current is turned on, pulling the bob downward, and adding energy to the system.


Contents

Introduction

Vernier Engineering Contest

Vernier recognizes instructors for creative uses of Vernier sensors to introduce engineering concepts and/or practices. Vernier Engineering Award »

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