Enhancing Car Alarm Audibility and Identification
When it comes to car alarm, it’s crucial to ensure that the audible alert is not only heard clearly but can also be identified as your own vehicle. Modern car alarm systems, unfortunately, tend to share similar alarm sounds, especially if they belong to the same brand. Moreover, due to legal noise restrictions, the alarm sound may not always be loud enough to reach your ears if the car is parked a distance away.
Amplifying Alarm Sound with Horn Activation
The circuit illustrated here is specifically designed to address this issue. It enhances the alarm sound by triggering the car’s horn(s) in addition to the standard alarm, making the alert more audible and attention-grabbing.
Utilizing Internal Signals for Enhanced Security
Internally, car alarm systems often provide a signal that activates optional features like the engine immobilizer or volume sensors (ultrasound sensors). This signal typically goes low when the system is triggered and returns to a high state when the alarm system is deactivated. This internal signal serves as a foundation for integrating additional features to enhance the security system’s effectiveness.
Circuit Operation: Enhancing Alarm Sound with Horn Activation
The circuit operates based on the alarm activation signal received through D1. In its idle state, T1’s gate remains high, causing the FET to conduct and keeping power FET T2 effectively turned off. However, when the system receives an active low signal, T1 switches off, allowing the timing capacitor C2 to charge through R2. Approximately 15 seconds later, when the voltage across C2 reaches a certain level, T2 begins to conduct, energizing relay RE1. This action provides the necessary path for the ‘lights flashing’ signal to activate RE2, enabling battery power to reach the car’s horn(s). Upon deactivation of the alarm system, the activation signal returns to a high state. T1 starts to conduct, rapidly discharging C2 through R3, leading to T2 being cut off, and subsequently, RE1 being de-energized. Diode D2 serves to suppress the back EMF generated from RE1.
Capacitors: Energy Storage Devices
Capacitors, essential electrical components, have the ability to store and release electrical energy. They consist of two conductors separated by a non-conductive substance. When activated, a capacitor swiftly releases stored electricity in a fraction of a second. This basic principle is exemplified in devices like parallel-plate capacitors.