Motor vehicle antitheft alarm system - has vibration sensor and RC delay circuit allowing driver to dismount

摘要

The alarm system is operated by vibration or by open or closed circuit loops. A timing circuit allows the owner to alight before the alarm circuit is switched on. A detector circuit is switched on or off by a key switch. On switch on a timing circuit inhibits a gate to which a vibrations sensor is connected. When the timing capacitor is charged it causes a timing monostable to be initiated. When this time has elapsed an alarm monostable is initiated for a predetermined time. During this period an astable commences to oscillate and switch on a transistor via an inverter. The transistor drives a vibrator or vehicle horn for each negative pulse on its base. A monostable operates if power from the battery is cut off.