Variable resistance electrical control units
AssigneeR. & D. Instruments Limited
InventorsCharles Norman Williams, Hugh Roberts
Life of this patent
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Abstract
An electrical control unit operable as a rheostat or a potentiometer comprising an electrical circuit portion of a resistive electrically conducting material formed on a support in a spiral configuration, a spindle mounted for rotation about the center of the spiral, an arm non-rotatably engaged on the spindle but slidable relatively to the spindle radially with respect to the axis thereof, an electrical contact carried on the arm to move radially therewith, to make contact with said circuit portion, and a spiral guide means aligned with the circuit portion spiral and co-operable with the arm to guide said arm radially, so that the electrical contact follows the circuit portion spiral to alter the effective electrical resistance thereof in use.
Claims7
An electrical control unit, comprising an electrical circuit portion of a resistive electrically conducting material formed on a support in a spiral configuration, a spindle mounted for rotation about the centre of the spiral and having a non-circular portion, an arm having a longitudinally extending slot non-rotatably engaged on the non-circular portion of the spindle to provide for sliding movement of the arm relative to the spindle and radially with respect to the axis thereof, an electrical contact carried on the arm to move radially therewith, to make contact with said circuit portion, and a spiral guide means aligned with the circuit portion spiral and co-operable with the arm to guide said arm radially so that the electrical contact follows the circuit portion spiral to alter the effective electrical resistance thereof in use.
Dependencies are inferred from the claim text.