Modern cars are now required to incorporate reverse car parking sensors, which provide drivers visual and aural warnings to assist avoid crashes when reversing.
These sensors identify objects behind the car using infrared or ultrasonic technologies.
The operational amplifier op-amp integrated circuit, IC LM358 will be used in this article to examine a simple reverse parking sensor circuit.
To identify impediments and notify the driver, this circuit is quite easy to design with basic parts including resistors, presets , LEDs, a buzzer and an IR pair.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistor | 10k | 1 |
| Resistor | 150Ω | 1 |
| Resistor | 1k | 3 |
| Presets | 10k | 3 |
| Integrated Circuit (IC) | LM358 | 2 |
| LED Red | 5mm, 20mA | 1 |
| LED Yellow | 5mm, 20mA | 1 |
| LED Green | 5mm, 20mA | 1 |
| Buzzer | – | 1 |
| IR Pair | – | 1 |
| Battery | 9 Volt | 1 |
Two LM358 Dual Comparator ICs are utilized to compare voltages in this automobile parking circuit, and an IR pair is used to detect obstacles.
The IR receivers output has a direct connection to all of the comparators non-inverting pins, and each comparator has a 10k presets attached to its inverting terminal for setting the reference voltage.
The comparator is set up in non-inverting mode.
Through a 1k resistor, one Red LED is connected to the output of the IC1 LM358, one Yellow LED to the output pin of the IC1 LM358 and one Green LED to the output pin of the IC2 LM358.
At Red LED, a buzzer is also added.
This system is mounted at the back of the vehicle, with the front side of the sensor facing the obstruction wall.
Let us say that the automobile is now returning to the wall or other obstruction in the parking space.
No LED will light up if the distance between the automobile and the obstruction is more than 15 cm.
Now, if the automobile approaches the obstruction and, assuming the greed light is on, it indicates that the car is approximately 15 cm from the obstruction.
The automobile is approaching the impediment more closely now, and when the yellow light comes or turns on, it indicates that the car is around 10 cm away from the obstruction.
The automobile is approaching the obstruction now, and when the red light shows, it indicates that the car is about 5 cm away from the impediment.
At the same moment, the buzzer begins to sound.
The automobile needs to stop right away or risk harm from the buzzer and red light.
Formulas:
The formulas pertaining to the operation of the infrared sensors and the LM358 op-amp as a comparator in a reverse automobile parking sensor circuit are essential to comprehending the setup and calibration of the system.
The pertinent formulas are as follows:
Compute the Current of an IR LED:
Ohms law is used to determine the current flowing through the infrared LED:
ILED = Vcc − VLED / RLED
where,
- ILED is the current through the IR LED.
- Vcc is the supply voltage of 9V
- VLED is the forward voltage of the IR LED around 1.2V to 1.5V
- RLED is the series resistor 1k with the IR LED.
Threshold of Op-Amp Comparators:
The output of the LM358 comparator circuit switches based on the threshold voltage Vref, which is adjusted using preset
The required sensitivity can be taken into account while adjusting the reference voltage:
Vref = Rpreset/ Rpreset+ Rfixed × Vcc
where,
- Rpreset is the resistance of the preset 10k
- Rfixed is any fixed resistor used in the voltage divider network.
- Vcc is the supply voltage of 9V
Current in LEDs and Output Voltage:
An output voltage will be applied to the buzzer and LEDs by the op-amp comparator when it turns on.
Presuming a high output about Vcc:
ILED = Vcc − VLED / RLED
where,
- VLED is the forward voltage of the LED around 2V for standard LEDs.
- RLED is the current-limiting resistor for the LEDs 1k
You may efficiently develop and calibrate your reverse automobile parking sensor circuit to guarantee correct and dependable operation by comprehending and utilizing these principles.
How to Build:
To build a Reverse Car Parking Sensor Circuit Using IC LM358 below mentioned are the steps to follow:
- Assemble all the components as mentioned in the above circuit diagram.
- Connect pin 2 of IC1 LM358 to front leg of VR2 preset.
- Connect pin 3 of IC1 LM358 to resistor R4 and yellow LED2 in series and ground.
- Connect pin 4 of IC1 LM358 to 3rd leg of VR1 preset as shown in circuit diagram.
- Connect pin 5 of IC1 LM358 to pin 5 of IC2 LM358.
- Connect pin 6 of IC1 LM358 to VR1 preset front leg.
- Connect pin 7 of IC1 LM358 to resistor R3 and red LED1 in series and ground.
- Connect pin 8 of IC1 LM358 to positive supply.
- Connect pin 4 of IC2 LM358 to ground.
- Connect pin 5 of IC2 LM358 to pin 5 of IC1 LM358
- Connect pin 6 of IC2 LM358 to front leg of VR3 preset.
- Connect pin 7 of IC2 LM358 to resistor R5 and green LED3 in series and ground.
- Connect pin 8 of IC2 LM358 to positive supply.
- Connect 2nd leg of VR1,VR2 and VR3 preset to positive supply, and 3rd leg of VR1,VR2 and VR3 to ground.
- Connect IR LED Rx and resistor R2 in series from positive supply to ground.
- Connect IR LED Tx and resistor R1 in series from positive supply to ground.
- Connect a buzzer one leg between resistor R3 and LED1 and second leg to ground.
- Connect positive supply to positive of 9V battery and negative supply to ground of 9V battery
Conclusion:
The LM358 integrated circuit reverse auto parking sensor circuit is a useful and simple design to improve vehicle safety when reversing.
The circuit helps to prevent collisions and accidents by giving the driver visual and auditory feedback through the use of an IR pair, op-amps, LEDs and a buzzer.
Gaining an understanding of and building this circuit can also help you understand how operational amplifiers and sensor systems function in electrical projects.