Strathearn Audio Limited

David Holt

Graham W McLean

An electric motor, particularly for driving a gramophone, a tape recorder or an electric instrument at a low rotational speed whereby an induction effect is utilized to achieve good starting torque and a reluctance effect to give good torque when the motor is locked in and running synchronously. The motor includes a stator assembly with a first plurality of pairs of primary pole pieces each pair constituted by a first metal part for the energization by an in-phase current and a second plurality of pairs of primary pole pieces each pair constituted by a second metal part for energization by an out of phase current. The respective parts also define slots constituting secondary pole pieces. A rotor assembly defines a plurality of further pole pieces having a pitch corresponding to the pitch of the secondary pieces, so that when the secondary pieces associated with the first plurality are opposite to the respective ones of the further pole pieces the secondary pole pieces associated with the second plurality of pieces are displaced with respect to respective ones of the further pole pieces by the phase angle between in-phase and out-of-phase currents.

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Stapleford, United Kingdom

David Holt