Telephone interface circuit
First Claim
1. A telephone interface circuit comprising:
- a speech circuit;
a control circuit that turns on upon receiving a supply of a forward direction trigger current so as to connect first and second telephone lines and the speech circuit, and that goes off upon receiving a supply of a reverse direction trigger current so as to disconnect the first and second telephone lines and the speech circuit;
a capacitor that charges and discharges charge supplied from the first telephone line; and
a hook switch that supplies charge accumulated at the capacitor when off-hook to the control circuit as a forward direction trigger current, and that supplies charge discharged from the capacitor when on-hook to the control circuit as a reverse direction trigger current;
the control circuit is a thyristor control circuit comprising a first transistor, second transistor, and positive feedback circuit;
a base terminal of the first transistor and a collector terminal of the second transistor are connected;
an emitter terminal of the first transistor is connected to the first telephone line;
a collector terminal of the first transistor branches into two, with one branch being connected to the speech circuit and the other branch being connected to the positive feedback circuit;
a base terminal of the second transistor branches into two, with one branch being connected to the positive feedback circuit and the other branch being connected to the capacitor;
an emitter terminal of the second transistor branches into two, with one branch being connected to the speech circuit and the other branch being connected to the second telephone line; and
the hook switch connects the capacitor and the first telephone line when off-hook, and connects the capacitor and the second telephone line when on-hook.
1 Assignment
0 Petitions
Accused Products
Abstract
A telephone interface circuit comprising a speech circuit, a control circuit turning on upon receiving a supply of a forward direction trigger current so as to connect first and second telephone lines and the speech circuit, and going off upon receiving a supply of a reverse direction trigger current so as to disconnect the first and second telephone lines and the speech circuit, a capacitor charging and discharging charge supplied from the first telephone line, and a hook switch supplying charge accumulated at the capacitor when off-hook to the control circuit as a forward direction trigger current, and supplying charge discharged from the capacitor when on-hook to the control circuit as a reverse direction trigger current.
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Citations
2 Claims
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1. A telephone interface circuit comprising:
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a speech circuit; a control circuit that turns on upon receiving a supply of a forward direction trigger current so as to connect first and second telephone lines and the speech circuit, and that goes off upon receiving a supply of a reverse direction trigger current so as to disconnect the first and second telephone lines and the speech circuit; a capacitor that charges and discharges charge supplied from the first telephone line; and
a hook switch that supplies charge accumulated at the capacitor when off-hook to the control circuit as a forward direction trigger current, and that supplies charge discharged from the capacitor when on-hook to the control circuit as a reverse direction trigger current;the control circuit is a thyristor control circuit comprising a first transistor, second transistor, and positive feedback circuit; a base terminal of the first transistor and a collector terminal of the second transistor are connected; an emitter terminal of the first transistor is connected to the first telephone line; a collector terminal of the first transistor branches into two, with one branch being connected to the speech circuit and the other branch being connected to the positive feedback circuit; a base terminal of the second transistor branches into two, with one branch being connected to the positive feedback circuit and the other branch being connected to the capacitor; an emitter terminal of the second transistor branches into two, with one branch being connected to the speech circuit and the other branch being connected to the second telephone line; and the hook switch connects the capacitor and the first telephone line when off-hook, and connects the capacitor and the second telephone line when on-hook. - View Dependent Claims (2)
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Specification