Telephonic communications – Substation or terminal circuitry – Hold circuit
Patent
1992-01-14
1995-02-14
Dwyer, James L.
Telephonic communications
Substation or terminal circuitry
Hold circuit
379377, 379386, 379387, H04M 174
Patent
active
053902491
ABSTRACT:
A telephone communication enable state maintaining circuit is disclosed, and the circuit includes a communication circuit 10, a communication operating circuit 20 and an operation maintaining circuit 30. The communication circuit 10 includes contacts 3,4,5, and a condenser C.sub.1. The communication operating circuit 20 includes a resistor r.sub.1, a condenser C.sub.2, a transistor 6 and contacts R.sub.3 a, R.sub.3 b, R.sub.1 a, R.sub.1 b. The operation maintaining circuit 30 includes contacts R.sub.1 c, R.sub.3 c, a resistor r.sub.2, a condenser C.sub.3, and a transistor 7. According to the present invention, telephone calls from the outside can be received, even if the telephone receiver is placed in an abnormal manner.
REFERENCES:
patent: 4903291 (1990-02-01), Tsurufuji et al.
patent: 4922529 (1990-05-01), Kiel
Dwyer James L.
Shehata M.
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