Infrared sensor module Circuit

Infrared sensors have wide variety of applications ranging from robotics and automation. IR sensors have been doing quite a great job in all these applications for many decades. This article teaches you to build a simple Infrared sensor module circuit which can be used with any application which needs detection or sensing.




A simple IR led and Photodiode used for emitting and sensing the IR beam. And Op Amp IC 741 is used as an comparator which in turn switches the output level as either logic 1 or logic 0. The Variable resistor RV1 used to tune the sensitivity of the detector by altering the reference voltage to the comparator. And at last LED D3 was meant as an indicator in case a IR beam is detected or reflected.

When the circuit is powered IR LED D1 emits Infra red beam. The photodiode D2 was connected in a reverse biased manner along with a resistor R2 in series. When there is no IR beam incident in the photodiode no current passes through it which in turn leads to no drop in voltage and inverting terminal of the Op Amp is fed with max voltage that is 5V. Since the voltage in the inverting terminal is more than the reference voltage at the “+” terminal of op amp the output stays LOW or logic 0.

When IR beam is reflected by any body which makes the beam to incident on Photo diode, current passes through it and in turn a drop of voltage occurs between the terminals. Now the reference voltage at the + terminal of Op amp is more than the – terminal. The output of Op amp switches to high or Logic 1 state.

This module will be highly useful to interface with Microcontroller for sensing since it provides the output in two logic levels which is compatible many microcontrollers.


IR LED and Photodiode must be placed as shown above


  • You can adjust the sensitivity of the module by altering the resistance value of the POT RV1.
  • Omitting the Comparator part and RV1 will give you a pure analog signal through which incident light intensity can be measured.
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Frank Donald

Frank Donald

Junior Network Engineer at Tata Communications
Frank Donald is an Electronics and Communication Engineer who loves building stuff in his free time. Video games, blogging and programming are the things he loves most

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12 Comments on "Infrared sensor module Circuit"

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I think when Jason asked “What was it’s purpose in the original module?”, he referred on the transistor. I am also curious regarding that, but hopefully the circuit works with or without it as well.


i am a little confused..!!!!
what is the working principle here???
the IR diode(D1) emits IR radiation and the photo diode(D2) picks it up right??
but in the actual circuit board they are side by side so ,then won’t the photo diode pick up IR radiation directly from the IR diode?????


easy understanding and compact design. i am new to this feild. wherther any body got the out put from this.

Andhika Pratama

Sorry i was new in electronics, but can you help me ? what is the name of the blue component is located under ic on the picture.
Thanks Before

Irish Electronics

On the picture there appears to be a Transistor but on the schematics it is not shown? Also no mention of it in the workings.