University College Cardiff Consultants Limited

The Secretary of State for Industry in Her Britannic Majesty's

Alan J Collins

John D McQuillin

Mazen R Husni

When an electrically conducting material is subjected to an alternating magnetic field local changes in the magnetic field adjacent to the conducting material are detected by a detector comprising a magnetoresistor or Hall crystal which generate an electrical signal when subjected to the magnetic field. The process and apparatus can be used to identify, classify and locate electrically conductive material. The detectors can be of the order of a few millimeters in size and so can be used to detect local changes in the magnetic field over correspondingly small areas of the material. The invention is particularly useful in identifying coins used in coin operated machines.

Apparatus for identifying an electrically conducting material

The present invention provides thin film magneto-resistive readout apparatus for providing readout from magnetic memory devices such as magnetic tapes, the apparatus comprising a thin film magneto-resistive readout head element, a narrow pulse generator for applying sensing current to the readout head element in the form of trains of narrow pulses, and a signal averaging circuit connected to receive output signals from the readout head element for deriving an average output signal for the pulses in each train.

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Risca, United Kingdom

Alan J Collins