Abstract: An impulse noise detector, for use in impulse noise suppressor circuits which are used for suppressing scratch noises in disc record players, comprises a rectifier operable on an applied signal to provide a rectified signal, a smoothing circuit for smoothing the rectified signal, a pair of delay and invert circuits operable on the smoothed signal for affording a corresponding plurality of time delayed signals, and a combiner for selectively combining the time delayed signals to afford an output which is indicative of the presence, in the applied signal, of impulse noise.

Abstract: Electrical equipment for controlling an electric motor for the horizontal movement of the pickup member of a disc-record gramophone towards and away from the center of the gramophone turntable comprises position-selector means which, when set to any one of a number of predetermined positions of the pickup member, start the motor and emit a normally constant speed-reference signal controlling the motor speed and, upon receipt of a position-identifying signal from the selected position, cause the motor to be de-energised, thus terminating the motor-driven movement of the pick-up member, individual position-detector means, each so constructed as to perform the dual function of emitting such position-identifying signal and of varying the normally constant reference signal in accordance with the residual distance of the pick-up member from the accurate location of the selected position, thereby varying the motor speed so that the position-detector means work, in conjunction with the motor, as an approach servo.