Background: A manufacturer of battery powered electric forklift trucks assembles in three overseas plants for local markets. Each market has different standards for battery voltages which range from 36 volts in the United States to 80 volts in Germany. Accessories such as headlights, horns, two-way radios, etc. all work on 12 volts DC.

Project: Product Resources was contracted to design and build a power supply that would accept any DC input voltage from 30 to 90 volts with a constant output voltage of 13.8 volts at up to 180 watts. Product Resources engineers used a single power MOSFET transistor switching at up to 100 kHz in a variable frequency regulator. The regulator was built into a rugged cast metal enclosure that served as a heatsink. The specification required that the regulator should start into a full load of incandescent lamps and could be connected with reverse polarity or short circuited for 24 hours without damage. Product Resources currently produces these regulators and ships them directly to the customer's plants in the U.S., U.K., and Korea. Thousands are in daily use worldwide.

Technologies: switchmode DC/DC converter, power MOSFET's, wide range input and short circuit current limits, aluminum sand casting, CNC machining, severe operating environments

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