"degraff" - 1 õppematerjal

Book Analog Interfacing to Embedded Microprocessors

frequencies. In fact, one way to find grounding problems is to use an artifi- cial ESD generator and zap the chassis of your equipment. The circuits most affected (or most often affected) are often those with grounding problems. Self-Induced ESD Any time you have a motor-driven system with belts, pulleys, plastic gears, or other insulating, moving components, you have the potential for self-induced ESD. Depending on the materials used, a belt running over a pulley can be an excellent Van DeGraff generator. Figure 8.7 illustrates a practical system that I worked on with serious self-induced ESD problems. A plastic band heater was wrapped partway around a rotating drum. Objects to be heated were guided under the heater, and the pressure between the heater and the drum performed a sealing action. The problem was that, somewhere between the prototype and production, someone discovered that they could get better heat transfer by changing the drum material. They changed it from a con-