Bcf Designs Limited

Raychem Limited

Anthony James Moore

Stephen Hunter Diaz

Gabe Cherian

David Crofts

John R Vinson

Stephen Morris

Electrical filter circuits are tested by connecting test apparatus to the filter circuit inputs, without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter circuit inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filter circuits have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results by a computer to determine characteristics of the filter circuit, such as values of the individual sub-components of the filter circuit. An interactive process is applied to successively improve the accuracy of the component value determinations over a range of frequencies. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

Method and apparatus for testing frequency-dependent electrical circuits

Electrical filter circuits are tested by connecting to the filter inputs without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filters have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a computer to determine the location of inflections in the curve and other characteristics of the curve. Methods are disclosed for determining the values of the individual sub-components of the filter. Where the filter is an L-section filter, an interactive process is applied to successively improve the accuracy of the component value determinations. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

Electrical filter circuits are tested by connecting to the filter inputs without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filter have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a compute to determine the location of inflections in the curve and other characteristics of the curve. Methods are disclosed for determining the values of the individual sub-components of the filter. Where the filter is an T-section low pass filter, an interactive process is applied to successively improve the accuracy of the component value determinations. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

Electrical filter circuits are tested by connecting to the filter inputs without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filter have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a compute to determine the location of inflections in the curve and other characteristics of the curve. Methods are disclosed for determining the values of the individual sub-components of the filter. Where the filter is an L-C filter, an interactive process is applied to successively improve the accuracy of the component value determinations. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

Electrical filter circuits are tested by connecting to the filter inputs without the need to connect to the filter outputs or to disconnect the outputs from a load. A signal generator of known source resistance applies a.c. signals successively over a range of frequencies to the filter inputs, and a voltmeter monitors the voltage across the filter inputs. Different types of filter have different characteristic shapes for the voltage/frequency curve, and processing is applied to the measured results in a compute to determine the location of inflections in the curve and other characteristics of the curve. Methods are disclosed for determining the values of the individual sub-components of the filter. Where the filter is C-section low pass filter, an interactive process is applied to successively improve the accuracy of the component value determinations. Using the techniques described enables the insertion loss of the filter also to be readily calculated by the computer.

A circuit protection device for protecting electrical circuits against voltage transients comprises a chip package which includes a threshold switch device formed from an amorphous composition.

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Cirencester, United Kingdom

Anthony James Moore