Communications: electrical – Systems – Call station
Patent
1974-08-20
1977-03-08
Caldwell, John W.
Communications: electrical
Systems
Call station
340283, 340384E, G08B 2100
Patent
active
040115550
ABSTRACT:
An alarm system which is particularly adapted for use in connection with an appliance, the system sensing the removal of the power supply plug from the convenience outlet to trigger an audio alarm. The system includes a one hertz oscillator circuit which feeds a one hertz signal to a one kilohertz oscillator signal including an input gate circuit, the output of the one kilohertz oscillator circuit feeding an output transformer connected to the audio signaling device upon triggering of the one kilohertz oscillator circuit. The system further includes a gating device, in the form of a controlled rectifier, the gate and cathode electrodes of which are connected to a source of alternating current supplied through the plug and convenience outlet assembly whereby the controlled rectifier is triggered to the conductive state to permit conduction of a multiple frequency signal through the output transformer and gate circuit upon removal of the power supply plug from the convenience outlet. There is provided a reset circuit including a reset switch which shunts the controlled rectifier, the reset switch being actuated from a position external to the appliance cabinet.
REFERENCES:
patent: 3346857 (1967-10-01), Cromer
patent: 3425050 (1969-01-01), Tellerman et al.
patent: 3553673 (1971-01-01), Fistell
patent: 3696380 (1972-10-01), Murphy
patent: 3765008 (1973-10-01), Lowry
patent: 3805231 (1974-04-01), Santoli
Hank Olson, "A One-Chip, Two Tone Generator," Apr. 1974, pp. 48, 49.
Caldwell John W.
Crosland Donnie L.
Markowitz Monte
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