Components required:

Principle:

IR sensors are used in the detection of objects, and obstacles. IR light is emitted from the IR emitter, which falls on the object and then reflects back. This reflected IR light is captured using an IR receiver and used to conclude the presence of the object. If the object is in the vicinity of the IR module, then the object’s presence can be detected. Otherwise, the object is said to be absent.

The IR sensor module has an IR emitter and receiver in the same module. The diagram below shows the IR sensor module.

The IR module contains 3 pins for the interface. Out of 3 pins two pins are VCC (3.3V/5V) and GND power supply. The OUT pin is the output pin which goes to a HIGH state when the object is present. When no object is detected OUT pin will stay at a LOW state. The major components in the module are the OP-AMP comparator, trim-pot, power LED and output LED. Trim-pot is used to change the sensitivity of the IR module (by varying the trim-pot we can change the distance at which the sensor can detect the object).

Circuit diagram:

Procedure:

1. Connect the IR module’s VCC and GND pins to Arduino’s +5V and GND pins respectively as shown in the circuit diagram.
2. Connect the OUT pin of the IR module to the Arduino board (pin 2) and declare it an input pin.
3. From the Arduino board connect the output (pin 7) to the +ve terminal of the LED. Connect –ve terminal of the LED to ground
4. Write the code in Arduino UNO software and run the program.
5. Move the object in front of the IR module and see the LED turning ON which indicates the presence of the object.

Working of object detection:

Whenever there is an object in front of the IR module, OUT of the IR module goes high. The IR module’s OUT pin is connected as the input to the Arduino board. The microcontroller in the Arduino board reads this signal and can conclude whether there is an object or not. The output is indicated through the LED connected to the Arduino board (shown in the breadboard).

The distance of the measurement (sensitivity) can be changed by varying the trim-pot. Variation in the trim-pot changes the reference voltage of the OP-AMP comparator. This

Flowchart for object detection:

Arduino Program for object detection:

int in_IRSensor = 2; // connect ir sensor to arduino pin 2
int out_LED = 7; // conect Led to arduino pin 13
void setup() 
{
  pinMode (in_IRSensor, INPUT); // sensor pin INPUT
  pinMode (out_LED, OUTPUT); // Led pin OUTPUT
}
void loop()
{
  int status_IR = digitalRead (in_IRSensor); //Read the IR sensor output
  if (status_IR == 1)
  {
    digitalWrite(out_LED, HIGH); // high on LED indicates object detected
  }
  else
  {
    digitalWrite(out_LED, LOW); // low on LED indicates no object present
  }  
}

The post Object Detection using the Arduino UNO first appeared on Student Projects.

Here is a simple IR sensor-based security system which will detect any movement and triger an alarm. This circuit is ideal for use in houses, banks, stores, and other restricted areas where a movement-based alert alarm is required. This circuit is based on an IR sensor in which an IR beam is continuously falling on a photodiode, and an alarm is activated anytime this Infrared beam is broken by any form of movement.

The circuit schematic is shown below.

This security burgler alarm circuit is simple to build and only requires a few components, which are mentioned below.

IR LED

An IR LED (infrared light-emitting diode) is a special-purpose LED that emits infrared rays with wavelengths ranging from 700 nm to 1 mm. So it is invisible to human eyes. IR LEDs are more commonly used in security systems and remote control devices.

Photodiode

A photodiode is a semiconductor device with a P-N junction that converts light into an electrical current. The resistance and output voltage of the photodiode alter in response to the amount of infrared light received.

LM358

The LM358 is an operational amplifier (Op-Amp), and it is used as a voltage comparator in this design. The LM358 contains two independent voltage comparators. We have used only one comparator, with inputs at PINs 2 and 3 and outputs at PIN 1. The voltage comparator has two inputs: one inverting and the other non-inverting (PIN 2 and 3). The output of the comparator (PIN 1) is High when the voltage at the non-inverting input (+) is greater than the voltage at the inverting input (-). If the inverting input (-) has a higher voltage than the non-inverting end (+), the output is LOW.

NE555

The 555 Timer is is configured as a monostable mode in this example. When a falling edge is detected on pin 2(trigger pin), the output voltage rises high for a predetermined duration.

Working of an IR Sensor

An IR LED serves as the emitter, while an IR photodiode serves as the detector. An IR LED emits infrared light, which is detected by the IR photodiode. The resistance and output voltage of the photodiode alter in response to the amount of infrared light received. In this circuit we will detect when there is no light falling on the photodiode and trigger an alarm.

How does the IR based burgler alarm circuit work?

As per the circuit diagram given above, a variable resistor is connected to inverting end of LM358(Pin 2) to adjust the sensitivity of the sensor. A junction of the photodiode and a resistor is connected to the non-inverting end of LM358(Pin 3). LM358 op-amp voltage comparator’s output (PIN1) is connected to the 555 timer’s Trigger pin. The 555 Timer is set to monostable mode in this example.

When the circuit is switched ON and when there is IR radiation towards the photodiode, the voltage across it drops, while the voltage across the series resistor R2 increases. Non-inverting end (pin 3) gets high voltage when compared to inverting end (pin2). Hence the output of the comparator is HIGH, because the comparator output is connected to the 555 timer’s trigger pin, the 555 output is low when Trigger pin 2 is high. As a result, the 555 timer output remains LOW when the IR rays fall on the Photodiode. Read this article to learn how the IR sensor works with the LM358 comparator.

Now when the IR radiation towards the photodiode breaks due to some movement, the voltage across it increases, while the voltage across the series resistor R2 decreases. Non-inverting end (+) gets low voltage when compared to inverting end (-). Hence the output of the comparator is LOW, because the comparator output is connected to the 555 timer’s trigger pin, the 555 output is HIGH when Trigger pin 2 is low. As a result, the 555 timer output becomes HIGH and the he buzzer beeps for a short time. By altering the value of resistor R1 or capacitor C1, the duration of the beep can be lengthened.

Inverting end of LM358 is connected to the 10k pot. Make the necessary adjustments to ensure that voltage comparison works properly.

So, give it a shot and let me know if you have any questions in the comments section below. I’ll be happy to assist you!

The post IR Based Security Alarm Circuit first appeared on Student Projects.

Here is the circuit diagram.

This car parking sensor circuit is simple to build and only requires a few components, which are mentioned below.

IR LED

An IR LED (infrared light-emitting diode) is a special-purpose LED that emits infrared rays with wavelengths ranging from 700 nm to 1 mm. So it is invisible to human eyes. IR LEDs are more commonly used in security systems and remote control devices.

Photodiode

A photodiode is a semiconductor device with a P-N junction that converts light into an electrical current. The resistance and output voltage of the photodiode alter in response to the amount of infrared light received.

LM358

The LM358 is an operational amplifier (Op-Amp), and it is used as a voltage comparator in this design. The LM358 contains two independent voltage comparators. We have used only one comparator, with inputs at PINs 2 and 3 and outputs at PIN 1. The voltage comparator has two inputs: one inverting and the other non-inverting (PIN 2 and 3). The output of the comparator (PIN 1) is High when the voltage at the non-inverting input (+) is greater than the voltage at the inverting input (-). If the inverting input (-) has a higher voltage than the non-inverting end (+), the output is LOW.

Working of an IR Sensor

An IR LED serves as the emitter, while an IR photodiode serves as the detector. An IR LED emits infrared light, which is detected by the IR photodiode. The resistance and output voltage of the photodiode alter in response to the amount of infrared light received. The IR sensor’s basic functioning concept is shown below.

How does the Reverse Car Parking Sensor circuit work?

As per the circuit diagram given above, a variable resistor is connected to inverting end of LM358(Pin 2) to adjust the sensitivity of the sensor. A junction of the photodiode and a resistor is connected to the non-inverting end of LM358(Pin 3).

When the circuit is switched ON and when there is no object near the IR LED and photodiode, then there will be no IR radiation towards the photodiode. Hence the voltage across series resistor R2 decreases. Non-inverting end (pin 3) gets less voltage when compared to inverting end (pin2). Hence the output becomes LOW and the LED turns OFF.

Now when there is an object near the IR LED and photodiode, the photodiode absorbs the IR generated by the IR LED after it is reflected by the object. When reflected IR hits the photodiode, the voltage across it drops, while the voltage across the series resistor R2 increases. Non-inverting end (pin 3) gets high voltage when compared to inverting end (pin2). Hence the output becomes HIGH and the LED turns ON.

Inverting end of LM358 is connected to the 10k pot. Make the necessary adjustments to ensure that voltage comparison works properly.

So, give it a shot and let me know if you have any questions in the comments section below. I’ll be happy to assist you!

The post Reverse Car Parking Sensor Circuit first appeared on Student Projects.