Creating a gadget that alerts your phone if someone disconnects a wire from the car battery can be achieved using a combination of a microcontroller, a Bluetooth module, and a simple circuit to detect the state of the battery connection. Here’s a simplified approach to create such a gadget:
Components Needed:
Microcontroller: Arduino Nano or similar.
Bluetooth Module: HC-05 or HC-06 for communication with your phone.
Relay Module: To interface with the battery connection.
Battery Connector Probe: Simple metal probe or wire to detect battery connection status.
Piezoelectric Buzzer: For local audible alarm.
Smartphone with Bluetooth: To receive alerts via a custom app or notifications.
Circuit Diagram:
Battery Connection Detection Circuit:
Use a relay module to monitor the connection between the car battery and its terminals. When the battery is connected, the relay should be energized (closed circuit).
Connect one end of the relay coil to the positive terminal of the battery (via a suitable resistor to limit current).
Connect the other end of the relay coil to ground.
The relay's common terminal (COM) should be connected to the microcontroller input pin.
When the battery is disconnected, the relay will open, signaling the microcontroller.
Microcontroller and Bluetooth Module:
Connect the microcontroller (Arduino Nano) to the relay module to detect changes in the battery connection status.
Connect the Bluetooth module (HC-05 or HC-06) to the microcontroller for wireless communication with your phone.
Buzzer for Audible Alarm:
Connect a piezoelectric buzzer to another output pin of the microcontroller. This will sound an alarm locally when the battery is disconnected.
Software (Arduino Sketch):
Bluetooth Communication:
Use Arduino IDE to program the microcontroller.
Implement Bluetooth communication protocols (e.g., Serial communication) to send alerts or notifications to your phone.
When the microcontroller detects a change in battery status (relay open), it should send a predefined message or data packet to the Bluetooth module.
Alarm Logic:
Program the microcontroller to activate the piezoelectric buzzer when it detects that the battery has been disconnected (relay open).
Ensure the buzzer stops sounding once the battery is reconnected (relay closed).
Smartphone Application:
Bluetooth App Setup:
Install a Bluetooth terminal app on your smartphone (available on both Android and iOS platforms).
Configure the app to receive data from the Bluetooth module connected to the microcontroller.
Set up notifications or alarms within the app to alert you when the battery status changes (disconnected).
Assembly and Testing:
Prototype Assembly:
Build the circuit on a breadboard or custom PCB according to the circuit diagram.
Ensure all connections are secure and properly insulated to prevent short circuits or accidental disconnections.
Testing and Calibration:
Power up the circuit using a suitable power source (e.g., battery pack or USB power supply).
Test the system by disconnecting and reconnecting the battery to verify that the microcontroller detects the status change and triggers the buzzer and Bluetooth module correctly.
Final Enclosure:
Once tested, transfer the circuit to a suitable enclosure to protect it from environmental factors and secure it within your car.
Cost Considerations:
The estimated cost for this project can vary depending on the availability and pricing of components in your region. However, aiming for around 300 rupees (~$4 USD) is achievable if sourcing components economically.
By following these steps, you can create a simple yet effective gadget to alert your phone if someone disconnects the battery from your car, providing an affordable security solution.