Intruder Alarms, 2nd Edition

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Intruder alarm system circuitry

This chapter looks at the three key circuits used in an intruder alarm system, i.e., detector circuits, power circuits and control circuits.

It is important to be able to recognize the uses and limitations of the wiring methods that are employed in linking the detection devices with the control equipment. This can be achieved in many different ways, be it open or closed circuit and single pole, double pole or using two- or four-wire circuits. In addition, monitoring devices must be understood: these may take the form of diodes, end-of-line resistors or resistive networks and multiplex buses. Line monitoring is being increasingly used and even in lower-risk applications, and represents the future of detection ...