This circuit is engineered to notify the user when an unauthorized individual enters a home. Whenever an obstacle is detected in the vicinity of the IR-sensitive Intruder Alarm, it initiates an interrupt signal. This interrupt signal is then conveyed to the speaker to promptly alert the user.
Outline
- 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:
In this system, the IR (Infrared) transmitter continuously emits IR rays, which are intended to be captured by the IR receiver. However, when an obstacle obstructs the path of these IR rays, they bounce back towards the IR receiver. As a result, the Op-Amp’s output goes high. Notably, the RESET pin of the 555 timer is linked to this Op-Amp output.
The output of the 555 timer stays low when the voltage at pin 4 of the 555 timer is low. However, when the voltage at pin 4 is high, the 555 timer generates a frequency that can be adjusted by modifying the values of resistors R1, R2, and capacitor C3.
When an obstacle is detected, and the IR receiver captures the IR rays, the Op-Amp’s output goes high, consequently causing the 555 timer’s RST pin to go high, and the speaker emits a sound.
Conversely, if the IR receiver fails to receive the IR rays, the Op-Amp’s output remains low, which keeps the 555 timer’s RST pin low as well. In this case, the speaker remains silent.
The 1uF capacitor serves as a filter for the NE555 timer’s output before it reaches the speaker.
Multiple infrared sensors are strategically positioned throughout the house in various locations. All these sensors are interconnected to the RESET pin of a common 555 timer. Whenever any sensor detects an intruder, the 555 timer’s reset pin goes high, activating the speaker alert.
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:
In this illustration, the 555 timer is employed as a freely running oscillator. When a high-level pulse is introduced at the RESET pin, it initiates the frequency generation process. Modifying the resistor values, R4 and R5, or the capacitor value, C3, can alter the frequency generated by the 555 timer.
In this configuration, pins 2 and 6 of the 555 timer are interconnected, permitting triggering at the conclusion of each timing cycle. Within this circuit, capacitor C3 charges through resistors R4 and R5 and subsequently discharges through resistor R5.
LM358 Op-Amp:
IF V1>V2 then OP = HIGH
IF V2>V1 then OP = LOW
The LM358 IC comprises two operational amplifiers, each equipped with both inverting and non-inverting inputs, along with a single output. When the non-inverting input voltage surpasses the inverting input voltage, the op-amp yields a high output, whereas when the inverting input voltage exceeds the non-inverting input voltage, the output becomes low.
Regarding the IR Transmitter, it operates on an operational voltage range of approximately 2 to 3V. To reduce the excess voltage, a resistor is placed in series with the IR LED.
The infrared receiver consistently operates in a reverse bias mode. When it receives IR rays, it functions as a near-closed circuit, while in the absence of IR rays, it exhibits 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.
