Step 1: Infra-red Sensor
IR transmitter will emit infra-red when powered. You can connect the IR transmitter like a LED together with a current limiting resistor. The current limiting resistor is used to prevent too much of current passing through the transmitter and burnt it. I am using 330 ohms resistor for the IR transmitter.
Step 2: How to "see" IR
The IR receiver that I am going to discuss is the normal IR receiver instead of 38kHz IR receiver. IR receiver detects the amount of infrared received and varies the resistance across the receiver. Therefore, we can measure the voltage across the receiver to detect the amount of IR received.
Step 3: Using Op Amp Comparator With IR
I am using LM 324 Low Power Quad Op Amp. LM 324 has four op amps, so I just use only one of them for this test.
Step 4: Schematic and Theory of Operation
(1) IR transmitter will directly shine to IR receiver. IR receiver is connected in reverse biased with a 1M ohm series resistor. This will create a potential divider to the op amp non inverting input, V+.
(2) A 100k ohm variable resistor is connected to the op amp inverting input. By adjusting the variable resistor, we can adjust the reference voltage of comparator.
(3) When IR receiver is blocked from IR transmitter, the resistance across IR receiver will increase. Thus the voltage at non inverting input will increase.
(4) Since the V+ > V-, the output of op amp will be 5V. In this case, it will turn off the LED. Only when V+ < V-, the output of op amp is 0V, thus LED lights up.
Step 5: Images
Step 6: Video
Video demo using IR sensor with comparator.
Step 7: Using Arduino With IR
The connection is pretty simple for IR receiver. All you need is connect from IR receiver to any of the 6 analog inputs of Arduino. In this case, I am using analog input A0.
Step 8: Code for Arduino
//Infrared Sensor Experiment
#define photodiode A0
lcd.print(" Infrared Sensor");
lcd.print("Analog Val= ");
int value = analogRead(photodiode); //Read analog value from IR receiver
//Convert each digit in decimal and display on LCD
Step 9: Images
Step 10: Video
Video demo on using IR sensor with Arduino
Visit my blog on IR sensor, http://iamzxlee.wordpress.com/2014/01/22/infra-red-sensor-ir/