Hello guys! In this instructable I'll teach you how to make a very simple proximity sensor using infrared LEDs and Arduino.
After several times trying to optimize it, I finally came up with something that is quite simple e precise. Just like my first instructable, this project is perfect for beginners in the arduino's world, with a few components anyone can make it. I hope you all enjoy it.

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Step 1: Materials

Picture of Materials
For this instructable you are gonna need:
- Arduino
- 1 IR LED receiver (photodiode with 2 pins, not the phototransistor with 3 pins)
- IR LED emitters (as much as you can get, but at least 2)
- 100K resistor (brown black yellow)
- Jumper wires
- Breadboard
- Electrical tape
- Buzzer(optional)

Be careful to don't mix up the LED receiver with the LED emitter, they all look the same.

Step 2: Preparing the sensor

Picture of Preparing the sensor
Before mount it, we should prepare the IR LED receiver to don't receive light from the sides, so than the sensor is more directional.
I use electrical tape to make it, but you can use a straw or anything that blocks the light from the sides.
Cut a small piece of electrical tape and wrap it around the IR LED receiver, forming a tube. Trim the edge with a pair of scissors until it's about 1cm long.
Have a look at images to see how I made it with electrical tape.
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blorgggg9 days ago
DhruvB17 days ago

I've been doing this with on IR Transmitter but it isn't working

neetahar6 months ago

am trying this code...but in my project i connected buzzer ...and the problem is no voltage at pin 11...bcoz of that buzzer is not genrated sound..wt can i do???Please help me.

look at my comment in this post, would you? ;)
I am done making it successfully, Alhamdulillah!

I am seeing a lot of people planning that instead of buzzer if you use an led, it doesn't blink. It's because you haven't done the following,
" Clear The Double Slash to Make the Function Call Uncommented in the Last Line within the Void Loop".

Even if you used a buzzer, it wouldnt work if you haven't uncommented the following.

Hi, your setup works great! However, I want to change it to a setup where the receiver and transmitter are disconnected from each other. That is: I will need 2 arduino's. For a correct setup I need to know at what frequency the receiver and transmitter LED's are flashing. How to find this frequency?

bilal.tiger made it!2 months ago

Good one. It can be used to sense distance and adjust value in code,where as if an IR Receiving IC is used it can only give ON or OFF state

aaaaoooo2 months ago

HEAT SHRINK TUBING MAY be used instead of the tape tube

dushu2 months ago

Would it make sense to switch off the LEDs in your code after checking the distance. The current code only switches them off momentarily. Considering that you're not using any current limiting resistors - the LEDs could get damaged.

sghosh212 months ago

everything works fine .........but in the serial monitor i can see some negative values coming up randomly.......which make my LED go crazy sometimes even in a static position(i used an LED instead of a buzzer).......i fixed it......but i wanted to know why was it happening .....????

dushu made it!3 months ago

Works like a charm. Thanks

2014-06-21 15.23.46.jpg
jobo993 months ago

does itwork with a phototransistor?

mintesinot8 months ago

we are trying to use a photo diode with for our project which is fire fighting robot with two continuous servo and one castor wheel but it does not work can you help us

ricardouvina (author)  mintesinot8 months ago


What is the problem? Have you tried using the Serial Monitor for debugging?

If you are using it outside, the sunlight may cause it to not work properly. The fire may cause it too.

MikeJGarcia10 months ago
Great sensor Mr Ricardo! I really enjoyed making it and even used it to create a gesture controlled LED cube. Check it out......but forgive the bad lighting in the vid.
ricardouvina (author)  MikeJGarcia8 months ago

Thank you! Excellent project you have made!

MauS091 year ago
Can ANYONE help me please. I have the project ALMOST running. The problem for me is that when i give the microcontroller power and burn the program to it it does absolutely nothing. But when i touch the cable that goes from A0 to the board it comes on. Why is that? Please help me.
ZacWolf MauS099 months ago
I ran into the same issue for awhile, and it turns out I had the anode/cathode wires for the receiver mixed up. I flipped it around and it worked prefectly.
ricardouvina (author)  MauS091 year ago
Probably you are using the resistor after the IR LED receiver, I recomend you to look up carefully the schematic and follows as it is, and check if all the wires are well fixed.
jpineda121 year ago
Specifically, what type of photodiode is needed here?
Commonly, we buy the emitter and receiver in pairs(at least I do), and I see mostly the pair TIL-32 and TIL-78. I can't assure you that these are the names since I don't remember, but with a lil' google search you can differ the emitter and receiver and their names.
jpineda121 year ago
What does 150-distance mean? Help!
The value 150 he imposed as a "threshold", where the "beeps" from the buzzer will repeat at decreasing rates, since the distance(variable) will get higher(because the object is getting close) providing the distance variable value to be inversely proportional to the real, physical distance measure.
jrešetar9 months ago
I did it as you said and I have one problem.
It works great but only when light is on. When I turn light off LEDs turn on with no obstacle in front of it.
Why is that so?
Please help me.
marios854310 months ago
Can you work this out with one ir led
VerDe144610 months ago
yeah that would work..

but i would like to suggest a good sensor for your motor...
you can use HC-SR04...cause it measures distance

well google is our may get your answer there.. :)
arocafor11 months ago
Hello sir..

Noob here. How can i reduce the range of the sensor? I want to use it as a hidden switch for a motor. Would that work?tnx
jpineda121 year ago
The buzzer does not make any sound. And the serial monitor does not vary. How to solve this? Help!
13, 9:32 PM.jpg
E1Mike jpineda1212 months ago
well, you need infrared leds, those in the picture seems to be normal "blue" leds, the infralight can not be seen be human eye, but in cameras seem to be like a purple light, u can buy infrared in any electronic store or you can use some from TV remotes
benjjo1 year ago
HI, Very thankful for your effort and code.

I have a no0b Q.
I know you've deliberately simplified the code for ppl like me so maybe this Q is redundant but i was wondering about your 1 millisecond delay. Would you get a more accurate result if the delay was shorter? And if so, is there a way to do that with PortManipulation? i.e.
tyty931 year ago
This project imposible to detect pulse rate if i modify the program?? Actually, may i know what the main function IR LED receiver and IR LED emitter??

Thanks :)
I am trying to find IR led receiver. But I can;t locate it. What is part no and where I can get it? Whenever I google I get ir receivers that are 3 pin and tuned to 38 khz. Please help.
infanati1 year ago
Hi, me again hehe. I tried replacing the buzzer with an LED and setting it on pin 13 but for some reason it isn't turning responding. this is the code im using.

int IRpin = A0; // IR photodiode on analog pin A0
int IRemitter = 2; // IR
infanati1 year ago
Hi, me again hehe. I tried replacing the buzzer with an LED and setting it on pin 13 but for some reason it isn't turning responding. this is the code im using.

int IRpin = A0; // IR photodiode on analog pin A0
int IRemitter = 2; // IR emitter LED on digital pin 2
int ambientIR; // variable to store the IR coming from the ambient
int obstacleIR; // variable to store the IR coming from the object
int value[10]; // variable to store the IR values
int distance; // variable that will tell if there is an obstacle or not
int LED = 13;

void setup(){
Serial.begin(9600); // initializing Serial monitor
pinMode(IRemitter,OUTPUT); // IR emitter LED on digital pin 2
digitalWrite(IRemitter,LOW);// setup IR LED as off
pinMode(11,OUTPUT); // buzzer in digital pin 11
pinMode(13, OUTPUT);

void loop(){
distance = readIR(5); // calling the function that will read the distance and passing the "accuracy" to it
Serial.println(distance); // writing the read value on Serial monitor
// buzzer(); // uncomment to activate the buzzer function

int readIR(int times){
for(int x=0;x digitalWrite(IRemitter,LOW); // turning the IR LEDs off to read the IR coming from the ambient
delay(1); // minimum delay necessary to read values
ambientIR = analogRead(IRpin); // storing IR coming from the ambient
digitalWrite(IRemitter,HIGH); // turning the IR LEDs on to read the IR coming from the obstacle
delay(1); // minimum delay necessary to read values
obstacleIR = analogRead(IRpin); // storing IR coming from the obstacle
value[x] = ambientIR-obstacleIR; // calculating changes in IR values and storing it for future average

for(int x=0;x distance+=value[x];
return(distance/times); // return the final value

digitalWrite(13, HIGH);
digitalWrite(13, LOW);

us2410981 year ago
hiii again !! i tried it but for some reason its not working ..... i mean wen i see through camera i see led lighted but it dont work as proximity sensor(buzzer doesnt make noise )
ricardouvina (author)  us2410981 year ago
Take a look at the serial monitor and check if the value varies.
thanks it was that problem only
Guizbo1 year ago

I have a practical question. You mentioned the maximum range to be about 25 cm.
In my project I want to measure the distance up to a mirror.

From what I understand, if the mirror reflects more light, maybe the range is higher. Is my assumption correct? and if so, what could be the maximum range in that situation?
ricardouvina (author)  Guizbo1 year ago
I said that the maximum range was about 25 cm, because it was what I measured, I can't tell if the range is gonna get higher or not. You should test it before you implement it.
Thanks for asking.
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