A magnetic stirrer is an indispensable
instrument in any laboratory
setting. Commercially available stirrers are costly and have a defined
life-span. The construction of a low-cost magnetic stirrer based on
pulse width modulation is described. The design reported uses mainly
recycled parts which results in a robust and efficient device at a
very reasonable cost of ∼US$17.50, which will be particularly
attractive in developing countries. The project requires a multidisciplinary
approach and can be utilized as a teaching exercise.