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The relationships that are shaping international component design in appliance controls are examined. Several new design principles that offer many advantages to the appliance manufacturer are discussed. An example demonstrating these international design principles is given. A common control that attempts to satisfy the power switching requirements of three different products, namely, a dishwasher for Europe, a refrigerator/freezer for Australia, and a window room air conditioning heat pump (with an electric heating element) for the North American market, is presented. The international differences that exist in power distribution systems, such as high-voltage two-wire/three-wire systems, 50/60Hz line frequencies, and 120/240 V line voltages, are discussed. Design practices to accommodate these changes and methods used for feature differentiation are reviewed. >

The use of 4, 8, and 16 bit microprocessors versus discrete digital electronics in appliance controls is discussed. The categories set forth are not intended to describe all microprocessor parts available, but rather to address general microprocessor technologies. Simple controllers that can compete in applications typically relegated to switches and mechanical timers are discussed, as well as more complex controllers such as those providing novel and useful features for top-of-the-line appliances. Guidelines are assembled for use in choosing the right processor for the job. A typical microprocessor-based control project life, from concept to finished product, is discussed. The costs associated in microprocessor design, development, and modification during the embryonic phase are addressed. The use of microprocessor technology versus discrete digital circuitry results in reduced parts count, smaller circuit boards, improved performance/reliability, potential cost reductions, increased flexibility, and decreased response times. >