Fire AlarmLights and Display Board Circuits

Car Lights Alert Schematic Circuit Diagram

Dashboard Warning Lights in Modern Cars

Modern car come equipped with various dashboard warning lights, such as the oil pressure warning light or engine management light, designed to notify drivers if any system is malfunctioning. Normally, these warning lights illuminate briefly upon ignition but should turn off shortly after. If one or more lights remain lit while the engine is running, it could indicate a problem with the vehicle that needs attention.

Alert System for Older Cars

Almost all contemporary vehicles include an in-built alarm to remind drivers if they’ve left their lights on when exiting the car. However, there are millions of older car models lacking this helpful feature. For owners of such vehicles, the current circuit could be the solution they’ve been seeking, providing them with the alert system they need.

Car lights alert Schematic diagram

Door-Activated Buzzer Circuit

The anode of diode D1 is linked to both the light switch and the car lights, while its cathode is connected to the 12 V buzzer. The other terminal of the buzzer is joined either to one of the door-switch contacts or to terminal 31B of the interior light cable. When any of the front doors, typically equipped with a switch (which is not always the case for older cars’ rear doors), is opened while the external car lights are still on, the buzzer initiates a humming sound. The circuit accommodates only two-door switches: S2 represents the driver’s door contact, and S3 corresponds to the front passenger door’s contact. If the buzzer activation by the front passenger door is undesired, incorporate diode D2 as illustrated and disconnect the wire between the contacts on the two doors.

Circuit Suitability and Diode Specifications

It’s crucial to note that this circuit is specifically designed for cars wherein the door contacts switch the interior lights to ground (a common configuration in most vehicles manufactured within the last decade). Diode D1 can be a light-duty type, like the 1N4001. But D2 must be a heavier-duty variant, such as the 1N5401, as it carries the current flowing through the interior lights.

 

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