This circuit is designed to alert the user when an intruder enters into the home. If there is any obstacle in front of IR sensor, it generates an interrupt signal. This interrupt signal is given to the speaker to alert the user.
Super Sensitive Intruder Alarm Circuit Principle:
IR transmitter always emits the IR (Infrared) rays which have to be received by IR receiver. When there is an obstacle in front of IR sensor, the transmitted IR rays are reflected back to the IR receiver. The output of Op-Amp is high when IR receiver receives the reflected IR rays. This output of operational amplifier is connected to the RESET pin of 555 timer.
Related Post: Security Alarm Circuit without using 555 Timer IC
The output of 555 timer is low when input voltage applied at pin 4 of 555 timer is low.
When input voltage at pin 4 is high, then 555 timer produces the frequency which can be adjusted by the different value combinations of resistors R1, R2 and capacitor C3.
- Obstacle Present → IR Receiver Receives IR Rays → Op-amp Output High → 555 RST Pin High → Speaker Produces the Sound.
- No Obstacle → IR Receiver does not Receive the Rays → Op-amp Output Low → RST Pin Low → No Sound
The output of NE555 is filtered by the 1uF capacitor and fed to the speaker.
Many IR sensors are arranged in house at different locations. The outputs of all these sensors are given to RESET pin of common 555 timer. When any sensor detects the intruder, the reset pin of 555 timer becomes high and speaker will produce the sound.
Super Sensitive Intruder Alarm Circuit Diagram:
- NE555 timer
- LM358 op-amp
- Pot – 10k, 4.7k
- IR transmitter
- IR receiver
- Red led
- Ceramic capacitors – 0.1uF, 0.01uF
- Electrolytic capacitor – 1uF, 16v
- Resistors – 10k, 100, R4,R5
- 2 resistors – 330 ohm
- Speaker
- Battery
Super Sensitive Intruder Alarm Circuit Design:
555 Timer: Here 555 timer acts as a free running oscillator. It will generate the frequency when high pulse is applied at RESET pin. The generated frequency of 555 timer varied by varying resistor values R4, R5 or by varying the capacitor value C3.
Here Pin 2 and pin 6 of 555 timer are shorted to allow the triggering after every timing cycle. In this circuit, capacitor C3 charges through the resistors R4, R5 and discharges through the resistor R5.
LM358 Op-Amp:
IF V1>V2 then OP = HIGH
IF V2>V1 then OP = LOW
LM358 IC consists of two operational amplifiers. Each Op- amp has two inputs (inverting and non – inverting) and one output. The op – amp output is high when non-inverting voltage is greater than the inverting voltage and it is low when inverting voltage is greater than non inverting voltage.
IR Transmitter: The operating voltage of transmitter is around 2 to 3V, to drop the remaining voltage we connect a resistor in series with IR led.
IR Receiver: It is always used in reverse bias. It almost acts as a closed circuit when it receives IR rays and it has high resistance when it does not receive any IR rays.
Also read the post – Motion Detector Circuit using NE555 Timer
Intruder Alarm Project Circuit Simulation Video:
How to Operate Super Sensitive Intruder Alarm Circuit?
- Give the connections according to the circuit diagram.
- Connect 5V supply to the circuit.
- Now place the obstacle in front of IR sensor then speaker produces the sound.
- Remove the obstacle now you will not get any sound.
- Disconnect the battery from the circuit.
Super Sensitive Intruder Alarm Circuit Applications:
- This circuit is used in homes and offices for security purpose.
Circuit Limitations:
- This circuit produces the sound even if there is any non-living thing in front of IR sensor.
35 Responses
hello there,can i ask you something? what is the specification of the speaker that have been used in this circuit?
thank you.
it is an 8ohms speaker
pls upload the whole video
What is the use of second led
Please check the circuit only one Led is present..Remaining two are IR transmitter and receiver..
can we use a push button instead of an ir-module.
does the circuit work because the simulation and circuit dia are different from one another. can the circuit b simulated on proteus.
does the circuit work because the simulation and circuit dia are different from one another. can the circuit b simulated on proteus.could you show me?
good morning
can you give any idea about extension of this project. example: alert message etc
Can a 6v battery used for this?
yess you can
MY LED IS BLINKING BUT SPEAKER IS NOT WORKING. WHAT VALUES HAVE YOU TAKEN FOR R4 & R5 AND CAPACITOR CONNECTED THROUGH PIN 5 OF 555 IC AS IN VIDEO YOU HAVE TAKEN A CAPACITOR OF 10UF WHEREAS THERE IS NO MENTION OF THIS IN THE CIRCUIT DIAGRAM.
PLEASE HELP
THANK YOU
I am doing the same circuit , my led is glowing fine but the speaker is not working.
How to rectify this problem?
can i use a 9 volt battery???
What’s the purpose of the 5K potentiometer connected at the output of the comparator ?
how can i keep it ringing after the first signal cut ?
. even after the obstacle is removed . and thank you
Sir , I am doing this for my electronics workshop project and it is not working . And also what is the significance of pot. , capacitor and resistor values .
What are the Values of R4 and R5?
I am khaleel
thank you sir,
please sir,what is the required current,voltage consumtion by the two sensors and the led.Because I want to calculate the values of the other components.
can i use same diode arrangement instead of IR Tx-Rx that also allows same flow for similar ckt …
e.g. for transmission process tx rplaced with fwd bias diode and rx replaced with reverse bias
and for receiveing 2nd diode is in reverse bias
or suggest me something similar to that os ir module , coz here IR TX-RX is not available
thanks
need ur reply
You can use a PIR sensor or ultrasonic sensor for detecting the intruder..
hai..sir iam doing this project….i want perfect details of every component used ,,,with video and give me detailed values of the components
Sir plz tell me how many distance work this circuit im from sri lanka thanks
Hello sir, could you show me the role of the second pot (4.7k ohm) in this circuit. Thank you.
Best regards
Is there a ready pcb for this alarm where I just have to insert and solder the components?
thanks
Is there a ready pcb for this project?
No currently we don’t have any PCB designed for this…
please can I replace the electrolytic capacitor with ceramic capacitor?
This is one of the circuit I was looking for and I have couple of questions
Is it possible to modify the circuit with a blinking LED instead of speaker if anything between the IR beam
What’s the maximum space between the transmitter and receiver for better results
what should be the distance between the IR sensor and the obstacle ??
why you tittle project as super sensitive
can the circuit be simulated on Proteus? please
please tell, how can we an extension of the project.please reply me
Can we use buzzer instead of speaker here
I need to know the values of r4 and r5.