This is an easy-to-construct and install "closed-loop" alarm that is readily extendable and ideal as a secondary back-up system.

A burglar alarm system can be as complicated or as simple as you wish. The need was for one that would offer a good degree of protection, without being horrendously awkward to install or operate.

It was decided, therefore, that no attempt would be made to detect an initial entry, since this would entail a switch on every outside door and window frame, and glass break detectors on panes of glass. Instead, sundry internal doors would be alarmed. This has the advantage of not requiring a delayed arming system, to cover exit after setting the alarm, or a delayed actuation, to allow the returning owner to disarm the system.