This circuit is designed to alert the user when an intruder enters into the home. If there is any obstacle in front of IR sensitive Intruder Alarm, it generates an interrupt signal. This interrupt signal is given to the speaker to alert the user.
- Super Sensitive Intruder Alarm Circuit Principle:
- Super Sensitive Intruder Alarm Circuit Diagram:
- Super Sensitive Intruder Alarm Circuit Design:
- Intruder Alarm Project Circuit Simulation Video:
- How to Operate Super Sensitive Intruder Alarm Circuit?
- Super Sensitive Intruder Alarm Circuit Applications:
- Circuit Limitations:
- Checkout the project output video –
Super Sensitive Intruder Alarm Circuit Principle:
The IR (Infrared) rays are always emitted by the IR transmitter and must be received by the IR receiver. The transmitted IR rays are reflected back to the IR receiver when an obstacle is in front of the IR sensor. When the IR receiver receives the reflected IR rays, the output of the Op-Amp is high. The RESET pin of the 555 timer is connected to the output of the operational amplifier.
The output of 555 timer is low when input voltage applied at pin 4 of 555 timer is low.
When the input voltage at pin 4 is high, the 555 timer generates a frequency that may be modified by changing the values of the resistors R1, R2, and capacitor C3.
Obstacle is present; IR Receiver detects IR Rays; Op-amp Output is high; 555 RST Pin is high; Speaker generates sound.
IR Receiver does not receive the Rays op-amp output low rst pin low op-amp output low op-amp output low op-amp output low op-amp output low op-amp output low op-amp output low op-amp output low op
The 1uF capacitor filters the NE555 output before it is delivered to the speaker.
Many infrared sensors are placed throughout the house in various locations. All of these sensors’ outputs are connected to the RESET pin of a common 555 timer. When any sensor senses an intruder, the 555 timer’s reset pin goes high, and the speaker goes off.
Super Sensitive Intruder Alarm Circuit Diagram:
Circuit Components:
- 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:
The 555 timer is used as a free running oscillator in this example. When a high pulse is applied to the RESET pin, it generates the frequency. Changing the resistor values R4, R5 or the capacitor value C3 changed the 555 timer’s produced frequency.
Here The 555 timer’s pins 2 and 6 are shorted to allow triggering after each timing cycle. Capacitor C3 charges through the resistors R4, R5 and discharges through the resistor R5 in this circuit.
LM358 Op-Amp:
IF V1>V2 then OP = HIGH
IF V2>V1 then OP = LOW
Two operational amplifiers make up the LM358 IC. There are two inputs (inverting and non-inverting) and one output on each Op- amp. When the non-inverting voltage is greater than the inverting voltage, the op-amp output is high, and when the inverting voltage is more than the non-inverting voltage, it is low.
IR Transmitter: The operational voltage of the transmitter is roughly 2 to 3V, thus we connect a resistor in series with the IR led to lower the remaining voltage.
The infrared receiver is always utilised in reverse bias mode. When it gets IR rays, it almost operates as a closed circuit, and when it does not receive IR rays, it has a high resistance.
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.
