Applying Precision Switches

In turning a circuit on or off, the average precision snap-acting switch changes its resistance by about 13 orders of magnitude in a couple of milliseconds, when its plunger moves about .001 inch. This same switch is able to control a 15 ampere, 240 volt heater, or the millivoltmilliampere circuit of a receiving antenna. Precision switches are designed to have, and maintain, uniform mechanical and electrical characteristics while controlling a wide variety of circuits in many different environments. Because of their versatility and small size, precision switches are used in an endless variety of equipment. They perform important functions in such diverse applications as production machinery, chicken brooders, submarines, computers, space vehicles, and medical instruments. When applied correctly, these switches perform well, and are a significant help in simplifying designs and reducing costs. The application of precision switches is an intriguing technical subject. It draws upon many disciplines, including solid-state physics, plasma physics, physical chemistry, metallurgy, stress and vibration analysis, circuit analysis, and many others. Yet, it can be expressed in down-to earth common-sense terms, and can be readily understood and applied without specialized background. The three aspects of switch use are mechanical, electrical, and environmental; each is covered in depth.