This circuit warns when a vehicle such as a car, jeep, bus, etc gets overheated, or its temperature rises above a safe level. The circuit will warn with a buzzer beep and an LED flashing. The circuit drains a very small amount of current in standby mode, which is about 400uA. It’s okay to have it attached to the car battery.
This easy circuit is going to be a great idea to get a warning before the engine overheats so you can test what is actually going on or whether the vehicle needs to cool down. Normally all cars have a temperature gauge but sometimes we fail to note it so it’s always nice to have a sound signal.
Hardware Components
The following components are required to make the Car Engine Overheat Detector Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Resistors | 10K, 1K | 2, 3 |
| 2. | Potentiometer | 100K | 2 |
| 3. | LED | 5mm | 1 |
| 4. | Buzzer | – | 1 |
| 5. | DC power supply | 5-15V | 1 |
| 6. | Capacitors | 10uF, 0.01uF | 1 |
| 7. | Transistor | 2N4403 | 1 |
| 8. | IC | NE555 Timer | 1 |
| 9. | Thermistor | 10K | 1 |
| 10. | IC | LM358 | 1 |
LM358 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM358
NE555 IC Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
Car Engine Overheat Detector Circuit
Working Explanation
The circuit shown here is using two ICs which are an LM358 which is a dual operational amplifier IC and a NE555 timer IC. The circuit is divided into two parts, the first part of the circuit is a temperature sensor built around an LM358 IC, the LM358 IC is working as a comparator in the circuit and the second part is a buzzer circuit built around a NE555 IC which is working as an astable multivibrator here. The beeping rate and the LED’s flashing rate can be adjusted with the help of a 100 K variable resistor used between NE555 IC’s pins 6 & 7, and the desired level of temperature on which you want to activate the buzzer can be selected with the 100 K variable resistor connected with the LM358 IC.10 K NTC thermistor is used for the measurement of temperature shifts.
Application and Uses
- It is mainly used as the detector alarm for heating in a car engine.
