Abstract: A portable power supply system utilizes a foot controller and a lightweight, sealed electric motor assembly which attaches to any International Standard E-Coupling handpiece. The foot controller is adaptable for use with either an AC/DC adaptor or a rechargeable battery. A coaxial cable connects the variable voltage supply from the foot controller to the low voltage, DC motor assembly. The motor assembly is sterilizable, lightweight, and quiet, making it ideal for use by dentists, oral or orthopedic surgeons, laboratory technicians, or anyone else desiring an economical, portable power supply for handpieces.