motor vehicle alarm tone generator switching device - has control unit incorporating switch and control signal transmission stage supplied from battery in circuit with alarm tone generator and signal reception stage

摘要

The switching device uses a switch (5) incorporated in a control unit (H) fitted in the vehicle via a rotary coupling (R) and used for opening and closing an alarm tone generator circuit. The vehicle battery (8) supplies the control unit (H), the alarm tone generator circuit and a signal reception stage (3) receiving command signals from control switches (1) incorporated in the control unit (H). The control switches (1) are coupled to a transmission stage (2) which superimposes the corresponding command signals on the DC voltage fed from the battery (8) to the signal reception stage (3) via the control unit (H). Pref. the current path (10) between the battery (8) and the signal transmission stage (2) incorporates a voltage stabilising circuit (308). ADVANTAGE - Prevents continuous alarm tone due to short-circuit or earth connection.