There are times when you either forget to close the car’s door or you don’t close it properly, this can be both harmful or dangerous for you and your car. So an alarm is important for such cases. In this tutorial, we are explaining a simple contact-less car door left open reminder alarm circuit. this circuit will produce a beep beep sound when the car is not closed properly and remind you. The whole circuit is portable and can be made on a PCB or a Veroboard and then fixed in a small enclosure before attaching it to the car.
The LDR should be fixed somewhere on the dome light of the car and make sure it receives only the dome light of the car. to do that use tape to cover all the other sides of the LDR so it doesn’t receive any other light and give false alarms.
Hardware Components
The following components are required to make Car Door Indicator Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Lithium Battery | 3V | 1 |
| 2. | IC | TLC555 | 1 |
| 3. | LDR | – | 1 |
| 4. | Transistor | 2N4401 | 1 |
| 5. | Buzzer | 3V | 1 |
| 6. | Resistor | 10KΩ, 1KΩ | 1, 1 |
| 7. | Ceramic Capacitor | 0.01µF | 1 |
| 8. | Electrolytic Capacitor | 10µF | 1 |
| 9. | Variable Resistor | 100KΩ, 1MΩ | 1, 1 |
TLC555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of TLC555 IC
Car Door Indicator Circuit
Working Explanation
The circuit can be operated with a 3V lithium coin battery and it lasts longer because the circuit won’t use any current in standby mode. When the LDR detects dome light it will send a signal to the circuit and the transistor will activate the IC. Now the IC will activate the buzzer. The IC used in this circuit is a low-power version of the NE555 timer IC i.e. TLC555. If you can’t find this then use a 7555 timer IC which is another low-power version of the NE555 timer IC.
Applications and Uses
- Vehicles
- Safety box doors
- House doors etc.
