Movement or shock detector - has LED and phototransistor for sensing movement of spring bearing small mass

摘要

The movement and shock detector comprises a support (3), a helical spring (1) and detecting elements. The helical spring (1) has one end (2) fixed to the support (3), and its other end (4) bears a small mass (5) which can oscillate. Pref. the axis of the spring (1) is vertical when the small mass (5) is at its rest position. The detecting elements are formed by a LED (7) sending light on a phototransistor (10). The phototransistor signal varies as a function of the amplitude and frequency of the spring's oscillation due to movement or shock and can start an alarm. A hollow cylinder (16) is used to limit the amplitude of the spring's oscillations.