Anti-theft device for engine propelled vehicles

Abstract

A circuit for inhibiting the operation of an engine after the engine has functioned for a specific period of time. The circuit basically includes a timing network, a concealed switch, a timing disable network, an audible alarm, and relay. When the engine is started by an unauthorized operator, who is unaware of the concealed switch, the engine will operate in the normal manner upon closure of the ignition switch. Closure of the ignition switch applies battery power to the timing circuit which starts to "time out". Subsequently, when the timing circuit "times out", battery current flows through the relay coil, its contacts close to thereby connect a capacitor across the ignition points of the engine. The engine is thereby disabled after the vehicle has travelled a relatively short distance. An authorized user of the vehicle, knowing the existence and location of the concealed switch momentarily closes the switch after the engine has been started but prior to completion of the time out cycle and thereby disables the timing network. This permits unrestricted operation of the vehicle. Since the concealed switch was only activated momentarily through a silicon controlled rectifier, the timing network will be automatically reset upon opening of the ignition switch.

Dependencies are inferred from the claim text.