Fault detector and current limiter

Claim 2

A fault detector and current limiter having an input terminal and an output terminal and being responsive to an input signal to supply an output potential from a potential source to said output terminal, said fault detector and current limiter comprising: a first controlled conduction means operable in response to said input signal at said input terminal to supply said output potential to said output terminal, a first current limiter means coupled to said first controlled conduction means and said potential source, said first current limiter means inhibiting the first controlled conduction means from supplying said output potential when the current through said first controlled conduction means rises above a specified magnitude, and coupling means coupling said first current limiter means to said output terminal whereby said current limiter means further inhibits said first controlled conduction means in response to the potential at said output terminal.

Claim 3

The fault detector and current limiter as set forth in claim 1 wherein said first controlled conduction means has a first control electrode and a pair of first output electrodes and said first current limiter means has a second control electrode and a pair of second output electrodes, said pair of first output electrodes being coupled between said potential source and said output terminal and said first control electrode being coupled to said input terminal, said second control electrode being coupled to the one of said first output electrodes coupled to said potential source and being coupled to said output terminal by said coupling means, and said pair of second output electrodes being coupled between said potential source and said first control electrode.

Claim 4

The fault detector and current limiter as set forth in claim 1 wherein said input signal is generated as a result of a loop current flowing in a telephone line so that said supplying of said output potential to said output terminal is indicative of the loop current flowing on the telephOne line.

Claim 5

A fault detector and current limiter having an input to receive first and second input signals and supplying to an output first and second output potentials from first and second potential sources, respectively, said fault detector and current limiter comprising: a first normally nonconductive conduction means coupled to said input and coupled between said first potential source and said output, said first normally nonconductive conduction means being maintained nonconductive in response to said input receiving said second input signal and being rendered conductive in response to said input receiving said first input signal so as to supply said first output potential to said output, a second normally nonconductive conduction means coupled to said first potential source and to said first normally nonconductive conduction means, said second normally nonconductive conduction means being rendered somewhat conductive in response to excessive current flow through said first normally nonconductive means such that said second normally nonconductive conduction means limits the conductivity of said first normally nonconductive conduction means so as to limit said excessive current flow, a normally conductive conduction means coupled to said input and between said second potential source and said output, said normally conductive conduction means being rendered nonconductive in response to said input receiving said first input signal and being maintained conductive when said input receives said second input signal so as to supply said second output potential to said output, and a third normally nonconductive conduction means coupled to said normally conductive conduction means and said second potential source, said third normally nonconductive conduction means being rendered somewhat conductive in response to current flow through said normally conductive conduction means attaining a specified value so as to inhibit the conductivity of the normally conductive conduction means and thereby limiting the current flow through the normally conductive conduction means.

Claim 6

A fault detector and current limiter having an input to receive first and second input signals and supplying to an output first and second output potentials from first and second potential sources, respectively, said fault detector and current limiter comprising: a first normally nonconductive conduction means coupled to said input and coupled between said first potential source and said output, said first normally nonconductive conduction means being maintained nonconductive in response to said input receiving said second input signal and being rendered conductive in response to said input receiving said first input signal so as to supply said first output potential to said output, a second normally nonconductive conduction means coupled to said first potential source and to said first normally nonconductive conduction means, said second normally nonconductive conduction means being rendered somewhat conductive in response to excessive current flow through said first normally nonconductive means such that said second normally nonconductive conduction means limits the conductivity of said first normally nonconductive conduction means so as to limit said excessive current flow, a normally conductive conduction means coupled to said input and between said second potential source and said output, said normally conductive conduction means being rendered nonconductive in response to said input receiving said first input signal and being maintained conductive when said input receives said second input signal so as to supply said second output potential to said output, and a third normally nonconductive conduction means coupled to said normally conductive conduction means and said second potential source, said third normally nonconductive conduction means being rendered somewhat conductive in response to current flow through said normally conductive conduction means attaining a specified value so as to inhibit the conductivity of the normally conductive conduction means and thereby limiting the current flow through the normally conductive conduction means.

Claim 7

The fault detector and current limiter as set forth in claim 4 including a first coupling means coupled between said second normally nonconductive conduction means and said output, and a second coupling means coupled between said third normally nonconductive conduction means and said output.

Claim 8

The fault detector and current limiter as set forth in claim 4 including a first rectifier means coupling said normally conductive conduction means to said input, and a second rectifier means coupling said normally conductive conduction means to said output.

Claim 9

The fault detector and current limiter as set forth in claim 4 wherein said first input signal is received at said input when a loop current is flowing on a telephone loop and said second input signal is received at said input whenever said loop current is interrupted such that said first and second output potentials are indicative of the flow of said loop current on said telephone loop.

Claim 10

A fault detector and current limiter having an input to receive first and second input signals and supplying to an output first and second output potentials from first and second potential sources, respectively, said fault detector and current limiter comprising: a first switching means coupled to said input and coupled between said first potential source and said output, said first switching means coupling said first potential source to said output in response to said input receiving said first input signal, a first current limiter means coupled to said first switching means, said first current limiter means inhibiting the coupling of said first potential source to said output whenever an excessive current flow occurs at the output, a second switching means coupled to said input, said second switching means coupling said second potential source to said output in response to said input receiving said second inpuT signal, and a second current limiter means coupled to said second switching means, said second current limiter means inhibiting said second switching means from coupling said second potential source to said output whenever an adverse condition occurs on said output.

Claim 11

A fault detector and current limiter having an input to receive first and second input signals and supplying to an output first and second output potentials from first and second potential sources, respectively, said fault detector and current limiter comprising: a first switching means coupled to said input and coupled between said first potential source and said output, said first switching means coupling said first potential source to said output in response to said input receiving said first input signal, a first current limiter means coupled to said first switching means, said first current limiter means inhibiting the coupling of said first potential source to said output whenever an excessive current flow occurs at the output, a second switching means coupled to said input, said second switching means coupling said second potential source to said output in response to said input receiving said second inpuT signal, and a second current limiter means coupled to said second switching means, said second current limiter means inhibiting said second switching means from coupling said second potential source to said output whenever an adverse condition occurs on said output.

Claim 12

The fault detector and current limiter as set forth in claim 8 including a first coupling means coupled between said first current limiter means and said output, and a second coupling means coupled between said second current limiter means and said output.

Claim 13

The fault detector and current limiter as set forth in claim 5 wherein said first coupling means includes at least a first resistor and said second coupling means includes at least a second resistor.

Claim 14

The fault detector and current limiter as set forth in claim 9 wherein said first coupling means includes at least a first resistor and said second coupling means includes at least a second resistor.