Communications: electrical – Systems – Call station
Patent
1976-01-05
1977-03-15
Caldwell, John W.
Communications: electrical
Systems
Call station
340271, 335205, 200 6162, G08B 1308
Patent
active
040127311
ABSTRACT:
The improved burglar alarm system of the present invention includes a housing which is secured around a doorknob rotatably mounted on a door. The doorknob shaft extends out through an opening in the housing. A magnet is positioned on the shaft and aligned with a magnetic field-responsive switch in the housing so that the switch is held open only when the shaft is in the fully unrotated resting position. The switch is part of a circuit which includes a power source, such as a battery, and an annunciator, such as a buzzer or horn. The power source is connected to the circuit through an "on-off" switch accessible through the housing to activate the system.
A pointer or the like indicates the resting, fully unrotated position of the shaft, preferably by reference to the magnet, and preferably conceals the magnet. This simple, compact inexpensive system utilizing only a single, inexpensive magnet-responsive switch detects surreptitious rotation of the doorknob shaft in either direction, as by a thief or burglar, when the system is activated and announces this act via a horn, buzzer, etc. to warn the occupants or residents of the house, store, etc. where the alarm is installed.
REFERENCES:
patent: 2874240 (1959-02-01), Ricks
patent: 3327300 (1967-06-01), Birrenkott
patent: 3760312 (1973-09-01), Shlesinger
Bissell Henry M.
Caldwell John W.
Wannisky William M.
LandOfFree
Burglar alarm system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Burglar alarm system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Burglar alarm system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-428745