Communications: electrical – Systems – Call station
Patent
1976-03-22
1978-05-16
Swann, III, Glen R.
Communications: electrical
Systems
Call station
340224, 343225, G08B 1308
Patent
active
040901823
ABSTRACT:
A security system gives an alarm when unauthorized persons gain access to a protected space by opening a door or window, etc., but permits access by authorized persons without giving an alarm. The alarm is given automatically when the door or window, etc., is opened, unless the alarm is silenced by operation of a concealable portable transmitter, intended to be carried by authorized persons. The transmitter when actuated transmits a control signal, which may be coded, to a receiver-driver, which then completes a shunt circuit around the door or window, etc., so that the latter can be opened without setting off the alarm.
In one embodiment of the invention, in which the receiver-driver depends upon house current for its operation, an alternative means of silencing the alarm is provided. If the house current fails, thereby rendering the receiver-driver inoperative, a second shunt circuit around the door or window, etc., is automatically armed, and the second shunt circuit can then be completed by manual operation of a lock-actuated switch. The key necessary to operate the lock is issued only to authorized persons.
REFERENCES:
patent: 3588866 (1971-06-01), Schlafly, Jr.
patent: 3757319 (1973-09-01), Hedin
patent: 3833895 (1974-09-01), Fecteau
patent: 3891980 (1975-06-01), Lewis et al.
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