Letter Re: Photocell and Seismic Intrusion Detection Systems
Jim: Could you tell us more about a seismic intrusion detection system? Until your recent comments on this being necessary for the security of a hidden retreat, I had never even heard of such a thing. There must be more novices like me who are soaking up like a sponge everything you write, and would be very interested in knowing more. Thank you, – Joe. JWR Replies: I cannot over-emphasize the need for a proper intrusion detection system for a retreat. The simplest are the photocell “driveway alarms” which are commonly used on farms and ranches in the west. Most …