Telephone line switch using an optocooupler
AssigneeFans Telecom, Inc.
InventorsYuan-Neng Fan, Shih-Ming Tung
Life of this patent
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Abstract
A telephone line connection and disconnection circuit has a diode bridge coupled to the telephone line which converts different voltages of the telephone line into a voltage referenced to ground. A switching circuit is coupled to the diode bridge which opens and closes a conductive pathway for connecting and disconnecting a telephony product from the telephone line. A resistive element is coupled to the diode bridge and the switching circuit which allows for the conductive pathway to be normally closed. An optical isolator is coupled to the switching circuit and the resistive element for sending a control signal to the circuit when required.
Claims12
A telephone line connection and disconnection circuit comprising, in combination:
- a diode bridge coupled to the telephone line which converts different voltages of the telephone line into a voltage referenced to ground;
- a switching circuit coupled to the diode bridge which opens and closes a conductive pathway for connecting and disconnecting a telephone product from the telephone line;
- and
- a resistive element coupled to the diode bridge and the switching circuit which allows for the conductive pathway to be normally closed;
- wherein the switching circuit comprises:
- a first transistor having three terminal wherein a first terminal is coupled to the round and a third terminal is coupled to the diode bridge and the resistive element;
- and
- a second transistor having three terminals wherein a first terminal is coupled to a second terminal of the first transistor a second terminal coupled to the resistive element and to the optical isolator and a third terminal coupled to round wherein the second transistor is an NPN transistor.
A telephone line connection and disconnection circuit comprising, in combination:
- a diode bridge coupled to the telephone line which converts different voltages of the telephone line into a voltage referenced to ground;
- a pair of transistors coupled to the diode bridge which opens and closes a conductive pathway for connecting and disconnecting a telephony product from the telephone line;
- and
- a resistive element coupled to the diode bridge and the switching circuit which allows for the conductive pathway to be normally closed;
- wherein the pair of transistors comprises:
- a first transistor coupled to the round and to the diode bridge and the resistive element;
- and
- a second transistor coupled to the first transistor to the resistive element to the optical isolator and to round wherein the second transistor is an NPN transistor.
Dependencies are inferred from the claim text.