The digital pendulum Available to Purchase

A rigid pendulum was attached to an inexpensive rotary potentiometer to which batteries had been connected. As the pendulum swung, a voltage proportional to the angle resulted and was fed to a PET 4016 computer equipped with an analog to digital converter. Position versus time data at rates ranging from 75 to 750 points/cycle were acquired with better than 1% accuracy for multiple cycles of several pendulums released from angles up to 90 degrees. Numerical solutions to the elliptic integrals describing large amplitude motion were compared with experimental data as were small amplitude curve fittings using the method of differential corrections. Agreement was excellent in both cases. Nine suggestions are made for using the digital pendulum for demonstration and laboratory work for students in introductory noncalculus courses through senior experimental work.