Abstract: A motion sensor has a ball of electrically conductive material in an annular ball race around which the ball can travel in response to motion of the sensor and electrical contacts spaced apart from one another around the ball race for electrical contact with the ball during such travel. A circuit responsive to electrical contact of the ball with the contacts detects the travel of the ball and, thus, motion of the sensor and a device is provided for selectively retaining the ball in an inoperative position spaced from the contacts, whereby wear of the contacts by the ball is avoided while the sensor is in a correspondingly inoperative condition.

Abstract: An anti-theft device for attachment to an object has an alarm generator for emitting an audible alarm in response to an alarm signal and a motion sensor for initiating the alarm signal in response to movement of the anti-theft device. A retaining member engages the object to secure the anti-theft device to the object and a device responsive to movement of the retaining member initiates an alarm signal in the case of tampering.