Curtis Instruments is the worlds largest manufacturer of instruments and motor speed controllers for battery-powered vehicles and equipment. Curtis is preeminent in timers and counters that measure and record equipment ......Curtis Instruments is the worlds largest manufacturer of instruments and motor speed controllers for battery-powered vehicles and equipment. Curtis is preeminent in timers and counters that measure and record equipment use. Its newest product is a full line of all-solid-state gages, other important products include high-efficiency DC/DC converters and other accessories of electric vehicles, and high-frequency on-board battery chargers.