Tuesday, May 21, 2024

Human Detector

Surveillance is an important aspect in security, especially with places like banks, jewellery shops and the like. Nowadays even small hotels and bakeries use surveillance systems to protect their properties. Currently there are two types of surveillance system available.

  • Passive surveillance system
  • Active surveillance system

Now our goal is to built a passive surveillance system that acts as a human detector when the system is fired. The materials required for this purpose have been listed below.

Hardware required

  • Any controller board (Arduino recommended)
  • Pyroelectric Infrared Sensor (PIR) (“HC SR-501”
  • Servo motor (minimum torque 1.4Kg/m2.)
  • 16×2 LCD module
  • Light Emitting Diode (LED)
  • Hookups and Protoboard

Controller board

Arduino is one of the leading controller board platform which provides a learning environment for electronics hobbyists and students. There are lot of versions of Arduino board available, but the common and the most economical is Arduino UNO r3. It also provides an integrated development environment (IDE) to develop our code and implement it.

Pyroelectric Infrared Sensor

PIR sensors allow you to sense motion, and are mostly used to detect if a human moves in or out of the sensor range. These are small, inexpensive, low-power, easy to use and don’t wear out. They are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR, “Passive Infrared”, “Pyroelectric” or “IR motion” sensor. Since it costs about 100 INR anybody can afford it.

Servo motor

Two types of Servo motors naturally available. AC and DC Servo motors. For all electronic and embedded applications DC servo motor is used, because AC cannot be stored in batteries. A servo motor is similar to normal DC motor, but it additionally contains a feedback element and the electronics circuit. Feedback element senses the position of the shaft and allows movement in particular manner. The PWM waves are implemented to drive the servo motor. It contains 3 Pins. Vcc, GND and Pulse. It normally works on (5-12)V.

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LCD module

Liquid Crystal Display is most commonly used in electronics projects because it can print all possible characters including numerical digits including special characters. Additionally it doesn’t require any breakout board or drive. It is all embedded into it making it easy to use. Here we have used 16×2 LCD module.

Light Emitting Diode

The most common and the coming up electronic component of the 21st Century is LED. Wherever you turn around, you can see an LED. It has a unique character, that it is capable of working on both AC and DC.  Its cheap, light weight, portable and capable of being easily replaceable. Here we have used LED for indication purpose.

Hookups and Protoboards

These are normally prototype building components which are used for interconnection of external peripherals.

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Software required

Arduino IDE (If Arduino is used): Download Here

Construction of the circuit

With the help of double sided tape stick the servo motor and the PIR together as shown below. Make sure the shaft of the motor rotates without any external disturbances.


Next we do the circuit connections as shown below. Connect the circuit carefully to avoid errors.

Human Detector Circuit
Human Detector Circuit

After connecting the circuit. Your prototype will look like as shown.

author prototype
author’s prototype of the human detector


Now it’s time to Rock and Roll. Open your Arduino IDE and paste the code from here. You can directly upload to it to your board as well.



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