A fault indicator apparatus employs a single indicating device such as a light emitting diode (LED) to provide an indication of all zones within a plurality of zones which exhibit a predetermined condition being monitored. In particular, the invention is employed in a multi-zone intrusion system where...http://www.google.fr/patents/US4498075?utm_source=gb-gplus-shareBrevet US4498075 - Fault indicator apparatus for a multi-zone intrusion system
Fault indicator apparatus for a multi-zone intrusion system
