Contact Encoder As Digital Potentiometer

66 EE 1988 ecoNTACT ENCODER AS DIGITAL The number of so-called autonomous, or stand-alone, applications found for microprocessors and microcontrollers increases daily with the introduction of new equipment. Dishwashers, small household utensils, cameras, test and measurement equipment, and cars, to mention but a few examples, now have some type of built-in microprocessor that affords ease of operation to the user. The microcontroller-driven power supply discussed in Ref. (I) is a good example of how advanced digital elec- tronics can be incorporated into an otherwise analogue test instrument. Inevitably, where a microprocessor is used, the need arises to provide a reliable user interface. Function keys are ad- equate as long as the required controls are relatively simple (e.g., the on/off switch). A problem arises, however, when an analogue value is to be set (e.g., volume or tone control on an AF ampli- fier). A keyboard is not suitable for this. Not entirely unsuitable, but rath...