Patent
1976-10-07
1978-05-30
Cardillo, Jr., Raymond F.
179 15W, 179 2A, 179 84R, H04M 164
Patent
active
040924963
ABSTRACT:
An automatic telephone answering device includes a diode bridge rectifier having its input terminals connected across a pair of telephone lines through a first switch, and its output terminals connected across a relay coil through a voltage controlled impedance, such as a Zener diode. A relatively high frequency, high voltage call signal is rectified by the bridge and breaks down the diode to energize the relay coil. This closes a relay switch to actuate a control circuit, whose outputs a) actuate a tape recorder unit to play back a prerecorded message to the caller, and b) simultaneously transfer the first switch to connect the tape recorder unit across the telephone lines through a line transformer. The breakdown voltage of the Zener diode is selected to be above the voltage level produced by sound (conversation) signals and busy tone signals, whereby the device presents a high impedance to such signals and is not actuated thereby.
REFERENCES:
patent: 2147820 (1939-02-01), Milde
patent: 3649762 (1972-03-01), Okamura
patent: 3688038 (1972-08-01), Hugyecz et al.
patent: 3688044 (1972-08-01), Konno
patent: 3716673 (1973-02-01), Meri
patent: 3818141 (1974-06-01), Jacobson
patent: 3941941 (1976-03-01), Simokat et al.
Ando Shizuo
Mizuno Hiroshi
Cardillo, Jr. Raymond F.
Pioneer Electronic Corporation
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