INTRODUCTION

Hello viewers, in this tutorial we will learn about how to make  INVISIBLE INTRUDER ALARM.

INVISIBLE INTRUDER ALARM is nothing but a simple infrared security system which lets you know whenever the field created by the infrared light is being intruded by any external source (may be thief). It is the system which you may have seen in the movie DHOOM 2 in diamond stealing scene by the hero, the security system which were used in that museum scene was infrared security system.

COMPONENTS REQUIRED

  • IR LED
  • IR Photo Diode
  • 100 K Resistor
  • 470Ω Resistor
  • BC547 Transistor
  • Buzzer
  • LED
  • 9 Volt Battery
  • Battery Clip
  • Bread Board

IR LED

IR stands for Infrared and LED stands for Light Emitting Diode which resembles Infrared Light Emitting Diode. It is a type of Led which emits Infrared Light. It’s operating voltage is same as the normal color emitting LED i.e. 1.5V and it has two legs, longer leg is anode which means it’s a +ve terminal and shorter leg is cathode which means it’s a –ve terminal.

IR PHOTO DIODE

IR Photo Diode is an electronic semiconductor device which senses the Infrared Light. Its bulging part is in black color so that it could easily catch or detect the Infrared Radiation or Emission. It has two legs namely anode and cathode. It looks like LED but unlike LED it is operated in reverse biased direction which means its longer leg i.e. is connected to –ve and shorter leg is connected to +ve for its proper operation as it will not work in forward biased direction because it’s a receiver not a transmitter. So here in our case we have used this device to detect infrared light interruption.

TRANSISTOR

Transistor is a semiconductor device which is basically of two types NPN and PNP. In PNP transistor, N-type semiconductor is sandwiched between two P-type semiconductors and in NPN transistor, P-type semiconductor is sandwiched between two N-type semiconductors. Transistors have three legs namely COLLECTOR, BASE and EMITTER. Here in this circuit we are using a BC547 transistor which is a very commonly used NPN transistor. You can use any type of NPN transistor such as BC548, BC549 etc. Its operation is very simple, whenever a current is applied in its base then the barrier between the collector and the emitter gets decreased and charge starts flowing from collector to emitter as both terminals gets shorted internally.

BUZZER

It is an electronic device which produces sound. It is also known as Piezoelectric Buzzer and it is of many types and comes in different-different sizes. Some of them are PCB buzzer, normal piezoelectric buzzer etc. Its operating voltage is 1.5V to 12V. It is widely used as an alarm because it produces a very high frequency sound at very high pitch volume with pee effect which is easily audible through very large distances too.

RESISTOR

Resistor is an electronic device which opposes the flow of current through it. It has two terminals and there is no polarity so it can be operated in both forward and reverse direction. Its value is characterized by its color of 4 bands present on it. Value of resistance is calculated by color coding. Here in our case we are using a 100k and 330Ω resistor.

LED

LED stands for Light Emitting Diode. Is a normal p-n junction diode which emits light whenever a current is passed through it. Is available in market in many different colors and of different power ratings. It has two terminals namely anode and cathode where longer one is anode and shorter one is cathode. It is operated in forward biased direction. Its operating voltage is 1.5V.

BATTERY

Battery is a voltage source device which stores charge and energy. There are many different types of batteries of different-different types of voltage ratings which are available in the market such as 1.5V, 3.7V, 4V, 6V, 9V, 11.7V, 12V etc. There are different types of batteries such as Lead-Acid battery, Lithium-Ion battery, Li-Po battery etc. Here in our case we are using a 9V battery.

BATTERY CLIP

Battery Clip is used to connect the battery from the circuit to the Bread Board. It has two wires in which Red one is +ve and Black one is –ve.

BREAD BOARD

Bread Board is nothing but a trainer board which provides convenience to the hobbyists. In bread board you can build up any circuit without any soldering. The thing you need is just to plug and play. It has dotted bread like pores in it in which you can insert the legs of your any electronic components such as resistor, transistor, diode etc for the operation.

MECHANISM AND WORKING

 

Its working is very easy and simple and it is composed of very few basic electronics elements such as IR LED, IR Photo Diode, LED, Resistor, Transistor, Battery etc. As we can see in this circuit there is two parts one part is transmitter part and other part is receiver part. The function of transmitter part is to transmit Infrared Signals in the form of infrared light and the function of receiver part is to receive the transmitted signal through IR Photo Diode. But here the main role is played by the circuit section of the receiver part i.e. by the inverting process of transistor. Here the IR Photo Diode is behaving like a switch because when the Infrared Light ray falls on the receiver part i.e. on the IR Photo Diode then it detects the IR signal and completes the circuit and circuit gets shot circuited as the current coming from the 100k resistor directly goes to ground through the IR Photo Diode rather going to the base of the transistor so the transistor remains in the off condition and buzzer also remains in the off state as the transistors is not providing any current to the buzzer (i.e. Ground through the emitter). But whenever the light is being interrupted or intruded by anyone or anything then the IR Photo Diode doesn’t conduct any current through it so the current coming from the 100k resistor directly goes towards the base of the transistor and activates the transistor and after that transistor starts supplying the ground to the buzzer and alarm goes on and LED turns ON which indicates that there is some interruption between the path (i.e. robbery)

CIRCUIT DIAGRAM OF INVISIBLE INTRUDER ALARM

TRANSMITTER PART

RECEIVER PART

WIRING AND CONNECTION OF INVISIBLE INTRUDER ALARM

STEP 1 OF INVISIBLE INTRUDER ALARM :

Connect battery clip to the Bread Board.

STEP 2 OF INVISIBLE INTRUDER ALARM:

Connect transistor to the breadboard

STEP 3 OF INVISIBLE INTRUDER ALARM: 

Connect one leg of the 100k Resistor to the +ve and another leg to the base of the transistor.

STEP 4 OF INVISIBLE INTRUDER ALARM:

Connect Collector of the transistor to the –ve leg of the Buzzer and connect +ve leg of the buzzer to the +ve supply.

STEP 5 OF INVISIBLE INTRUDER ALARM:

Connect –ve leg of LED to the collector of the transistor and +ve leg of the LED to the 470R (ohm) resistor and connect another leg of resistor to +ve supply.

STEP 6 OF INVISIBLE INTRUDER ALARM:

Connect longer leg of IR Photo Diode to the ground and shorter leg to the Base of the transistor.

STEP 7 OF INVISIBLE INTRUDER ALARM:

Connect emitter of the transistor to the –ve (Ground).

TRANSMITTER PART OF INVISIBLE INTRUDER ALARM

STEP 8 OF INVISIBLE INTRUDER ALARM:

Connect one leg of 470R (ohm) resistor to the +ve supply and another leg to the IR LED’s longer leg i.e. anode (+ve) and also connect the shorter leg(-ve) of the IR LED to the Ground.

STEP 9 OF INVISIBLE INTRUDER ALARM:

 Make sure that you have maintained proper gap between the transmitter part and the receiver part and then connect the Battery to the Battery Clip.

STEP 10 OF INVISIBLE INTRUDER ALARM:

Now it’s completely ready for the use. So, whenever the light is being intruded then alarm will go on along with the LED.

OFF CASE OF INVISIBLE INTRUDER ALARM

ON CASE OF INVISIBLE INTRUDER ALARM

YOU reached here that means you have complected the project  of INVISIBLE INTRUDER ALARM.

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This is Enamul Hassan, an Electrical and Electronics Engineer. I love discovering new things. I share my knowledge in this blog.

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