Reverse Car Parking Sensor Circuit

Published  August 23, 2015   85
S Saddam
Reverse Car Parking Circuit using IC LM358

This car parking assistant can protect your car from any damage while reverse parking. It indicates the distance of car from any object and raise an alarm when it reaches close to the wall or the object and needs to be stopped. This car parking sensor circuit is quite easy and uses few commonly available components which are listed below.


Required Components

  • IC LM358 - 2
  • 10k Resistor  - 1
  • 1k Resistor - 3
  • 10k POT - 3
  • 150 Ohm Resistor - 1
  • Bread board - 1
  • 9 Volt Battery  - 1
  • Battery Connector - 1
  • LED  - 3
  • Buzzer - 1
  • IR Pair - 1                


LM358: LM358 is a Dual Low Noise Operational Amplifier which has Two Op-Amp in a single chip. This is a general purpose op amp which can be configured in many modes like comparator, summer, integrator, amplifier, differentiator, inverting mode, non- inverting mode and many more.


To design this car parking system circuit, we placed an IR transmitter receiver pair at the rear side of the car. IR transmitter transmits Infrared signal or rays into the environment continuously. When these transmitted IR rays reflect back to IR Receiver after striking on an obstacle, some voltage difference generates across this IR receiver LED. This generated voltage difference depending upon the power of IR rays that are reflected back to the receiver. More powered signal leads to more voltage difference. This voltage difference is used in our project to measure the distance. Here more voltage difference indicates the lesser distance from the object. Here we have shown distance from the obstacle by using three LED’s. Meaning of these LED’s are explained in working of this project.

Block Diagram for Reverse Car Parking Circuit


Circuit Diagram and Explanation

In this car parking circuit we have used an IR pair for detecting obstacle and two LM358 Dual Comparator ICs for comparing voltages. Comparator configured in non-inverting mode and 10 K potentiometer is connected at its inverting terminal for adjusting reference voltage and IR receiver’s Output is directly connected at non-inverting pins of all comparators. One Red LED is connected at output of U1:B IC(LM358), a Yellow LED is connected at output pin of U2:A IC(LM358) and an Green LED is connected at output pin of U2:B IC(LM358) through a 1K resistor. A buzzer is also added at Red LED.

 Car Parking Circuit Diagram



We have shown the reference voltage and relative parameters in the below table. But one can set distance by changing the value of potentiometer.

Obstacle v/s Vehicle

LED status

Reference Voltage


not close



Greater than 15 cm


Green ON

2.0 Volt

About 15 cm

More Close

Yellow ON

4.0 Volt

About 10 cm

More Close

Red ON

6.0 Volt

About 5 cm


Car Damaged


About 0 cm


This system is placed at the rear of the car and sensor’s front side toward the obstacle (wall). Now suppose car is moving back toward the wall or obstacle in the parking slot. If distance between car and obstacle is more than 15 cm then no LED will glow. Now if car moves toward the obstacle and suppose greed light turned ON, it means car is about 15 cm away from the obstacle. Now car is moving more close toward the obstacle and yellow light appears or turned on it means car is about 10 cm away from the obstacle. Now car is moving closer toward the obstacle and red light appears it means car is about 5 cm away from the obstacle and same time buzzer start beeping. Buzzer and red light indicates that the car need to stop now otherwise car may be damaged.



Have any question realated to this Article?

Ask Our Community Members


Submitted by yashraj on Sun, 11/22/2015 - 15:47


we made the exact circuit on the bread board but we are not getting proper sensing through the ir pair we checked the ir pair its not faulty . when we place the power supply all the leds are glowing even if we remove the resistor all the leds are glowing what shall we do to make sure one led glows at a time and we get proper sensing

The circuit is correct, you need to adjust the values of three potentiometers by rotating the knob, Rotate the knobs until LEDs get turned OFF, now take some object in front of IR pair, LEDs should get turned ON. Now you should set the sensitivity of three LEDs separately by rotating the respective knobs, like Green LED should be most sensitive and Red LED should be least sensitive.

75cm can be obtained from this circuit, otherwise provide LED the optimal(max) power supply or use convex lens at photodiode or use a powerfull IR LED. Also try using 100k variable resistor to this circuit.

Submitted by Özge on Thu, 12/17/2015 - 14:13


We set circuit on the breadbord but we can not change volt for each led by potantiometer. How we can operate this circuit

Submitted by KILTON ROY on Wed, 02/24/2016 - 17:16


sir i do not understnd the circuit u have upload and original circuit

sir kindly tell me specification of recve resistr and what is the fuction of second ic lm358 there u did pin num 3 and 5 short but why? circuit mention correctly plese sir? i need this for my final year projt? so plese hele me sir

there is only two IC's are used.
here we have used LM358 which is dual op-amp IC.
mean single IC consists two op-amp inbuilt.
so here is four op-amp but we used three of them.

for more detial read data sheet of lm358.

Submitted by adi on Sun, 06/24/2018 - 19:36

In reply to by saddam khan


yes. but in the schematic every single op-amp have its own 8 & 4 pin. so its 3 different ic's??
(sorry for bad english)

Submitted by KILTON ROY on Fri, 02/26/2016 - 23:13


sir there you used 150ohm or 10 k resiston on recver diode and what is the specification of pot have used sir ?

Submitted by Kay Hanes on Thu, 03/03/2016 - 07:38


I have been trying to get this circuit to work and it seems to work opposite, turns off when something is very close and on all the time. I adjusted the pots and it doesn't fix it. Also, the schematic is not correct for using a 150 Ohm resistor in the call out, it shows 2 10K. Can you please help me?

You must have messed up with the inverting and non inverting ends of op amps, you have connected terminal + connections to - terminal and vice versa. I recommend you to read about LM358, it is a dual opamp IC, in which we have used 2 opamps of one IC and 1 opamp of another IC, means we have used total 3 op amps out of 4 from 2 LM358 ICs. Please go through its datasheet and understand the working of an Op-amp IC.

Submitted by hai on Tue, 03/08/2016 - 14:59


Hi I bought aftermarket car parking sensor device
I install in front bumper. Too much noisy. I plan to reduce rage from 2 meter distance to 1 meter distance . any help that I can do something on the circuit board

Submitted by Jack on Sat, 03/12/2016 - 03:01


Hi there! In the above circuit we have 1 Tx and 1 Rx sensor. Would be possible implement 2 or even 3 pairs of Rx/Tx?

Thanks in advance,

Submitted by KILTON ROY on Sun, 03/13/2016 - 13:45


sir can u tell me what is the frequency range transmit from the transmitter via infarred led and voltage value? and also at that time reciver point voltage value is what? sir kindly tell me ? this is my final year project? and also there are non inverting pin also short sir?

Submitted by Pranav on Sun, 03/20/2016 - 08:31


Sir, thank you for the circuit and the explanation
I want to know if we could make the same circuit sound when each LED glows

Submitted by David on Thu, 05/05/2016 - 15:26


Maddy can you upload the maths calculations of how resistance you put at the potenciometers related with the voltage? Thank you

dear sir ;

                  i need to change distances  green  is 30cm , yellow   is 15cm and  red is 5cm it's possible .if it's possible please tell me about this,,,

       thank you ;

       v.s rao.



Submitted by Arang Ariawan on Sat, 07/02/2016 - 19:02


"I have to try,all your instruction but very close not more 15cm.
Any solution to make more 50cm..thnk's

This question is already answered above. 50cm can be obtained from this circuit, otherwise provide LED the optimal(max) power supply or use convex lens at photodiode or use a powerfull IR LED. Also try using 100k variable resistor to this circuit.

Submitted by sankha on Mon, 08/08/2016 - 09:31


It works at day light. but at night ,when the light is low it works very badly..
Sir , please help me..

Submitted by ASHISH A. KUMBHAR on Mon, 08/22/2016 - 15:19


150Ohm register is burning while operating the ckt we got the same results but as time pasing the ckt sensitivity is changing and 150 ohm register is burning please help us
What modification we have to do?

Submitted by ASHISH A. KUMBHAR on Tue, 08/23/2016 - 19:21


Yes We used 9v power supply but it is still burning as time passing & ckt sensitivity is changing as time passing for every trial we have to adjust the presets what should we do

Submitted by shanthi on Wed, 09/07/2016 - 09:03


How can this concept be reversely operated as buzzer for long distance indication and no sound for short distance pls reply soon

Submitted by charlie on Sun, 11/06/2016 - 17:22


Maddy ,,
What is the potentiometer value we want to keep for glowing the LED......

Submitted by Bharath on Mon, 11/07/2016 - 16:59


Sir I have did the project but not on bread board I did the project on general purpose circuit came very well..sir I want u to see the model..

Submitted by Aashiq Mohamed on Wed, 11/09/2016 - 21:40


The buzzer is not working when I simulated it in Proteus. When I connected it in parallel with the LED, it stops working.

Submitted by sidra on Mon, 11/28/2016 - 22:44


How we can detect the pole behind the left and right rear lights?
In which configuration we can use two other IR sensors for detecting the pole described above?
plz reply me as early as possible

Submitted by Aletrina on Fri, 01/20/2017 - 08:09


Hello, does someone know about how long does the battery will last? Or can I power this circuit from my car battery?

Submitted by CC on Mon, 02/20/2017 - 10:45


Hi, we made the exact circuit, and once the power supply is connected all the LED's are glowing, then by rotating each potentiometer knob all LEDs turned off. What to do next? how to set the sensitivity of each LEDs?

em expecting your reply soon, thank you! ^_^

Submitted by Em-m on Sat, 03/11/2017 - 11:01


Hello, we also made the exact circuit, but everytime we're connecting the power supply, the leds just keep on glowing. We tried turning the knobs of the trimmers but the glowing leds are still turned on. Please helppp. Thank you!

Submitted by prabha on Fri, 03/17/2017 - 14:10


connection are correct but LED is not glowing. what should we do now?

Submitted by usman on Fri, 05/12/2017 - 17:07


Can you please send me a clear picture off ur breadboard thanks

Submitted by Amir on Tue, 05/30/2017 - 19:29


Hello sir, I have made the circuit as per the diagram. But all the LEDs are glowing together at 5 cm. The LEDs are not glowing at 10 and 15 cm. What should I do?

Submitted by joel on Sun, 10/15/2017 - 11:31


sir y u put 3 ics in the circuit and on the breadboard only two?

Take a close look at the name of IC in circuit diagram. They are U1A and U2A and U2B.

This means that there are only two IC U1 and U2. Since LM358 is a dual package op-amp it has both U2A and U2B inside it. Similarly U1 also has A and B, but we have left U1B to be free

Submitted by Hassan on Sun, 12/03/2017 - 01:30


I've made the same circuit on proteas as well as on bread board but both of them aren't working.

Submitted by HR Rufus on Sun, 12/10/2017 - 17:50


Can I know how many people have made this and succeed? Because I am having a problem because the LED keeps turned on even though I already change the sensitivity on the pot. Can someone help me with this?

Submitted by tom on Mon, 02/05/2018 - 17:12


what does the D5 do because i am lost on how the it can have the negative is connected to the positive

Submitted by Muhammad abuzar on Mon, 07/09/2018 - 08:27


hey guys what did you think its a correct circuit??? its not a correct circuit. he has used 2 ic's on bread board.while there are 3 ic's on proteus schematic format.