http://www.domain-hosting-server.com/News/principles-of-a-motion-alarm-detector/ The principles by which motion detector alarms operate are complex. Type motion alarm detector into any search engine and you will be overwhelmed by the information returned. In this article we will look at just the very basic principles behind the operation of these devices. First, there are active . Thu, 11 Mar 2010 12:13:56 UTC en