| 摘要 |
<p>PURPOSE:To prevent the occurrence of theft, by a method wherein the presence of an engine is decided through detecting of an electrical noise generated in an engine room due to the starting of the engine, and if the engine is not keyed when the engine is started, an alarm is sounded. CONSTITUTION:Electrical noise, generated as a result of the starting of an engine 2, is picked up by a nozzle 1, and the high frequency of the picked up voltage is cut by a capacitor 3 to amplify it by means of an amplifier 4. An output voltage from the amlifier 4 is rectified by a diode 5, and is smoothed by resistors 6 and 7 and a capacitor 8 to input it to a transistor 9. This brings a signal (a), entering a NOR circuit 15 from a collector, into L. In this case, when an engine is started in a condition that the engine is not locked by means of an engine key 11, or when theft occurs, a signal (b) entering the NOR circuit 15 form a switch 12 is brought to L. As a result, the input of the NOR circuit 15 is brought to L and L, and thereby an output is brought to H, resulting in actuation of an alarm device 18.</p> |
