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| IR sensor circuit diagram |
A simple IR proximity sensor circuit diagram is shown above.
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What is IR sensor
An infrared IR sensor is a device which is widely used in electronics to detect the presence of IR radiation and do a task according to our needs.
The IR radiation is a light which is invisible to human eye, so it need a special sensor to detect and process the values from the radiation.
The most common and cheap method of sensing these signal is by,
» Using a photo diode sensor
» Using a photo transistor sensor
» Using special photo detection sensors like TSOP 1738 ic sensor
In electronics there are mainly two types of infrared sensors,
1. Active IR sensors
2. Passive IR sensor
Active IR sensors
These are sensors which need a light to stimulate it's activity and a photodiode to monitor the present values.
As an object moves or come in front of the ir sensor and diode sensor some portion of light is reflected and is detected by receiver diode.
These type of sensors are also known as proximity IR sensors.These sensors used in burglar alarms, vehicle obstacle detection etc.
PIR sensors (PIR sensor)
A pir sensor is a device which is commonly used in electronics to detect a motion.These devices has inbuilt Ir receiver to receive IR radiation.
We know that every human being,animals are radiating a small amount of heat in the form of IR radiation.These radiation is detected by the pir sensor and activate it's output.
Components required
Ic - LM356
IR LED - 1 nos
Photo diode - 1 nos
LED - Green
Potentiometer - 10 kiloohms
Resistor - 220 ohms(half watt), 10 kiloohms, 100 ohms, 4.7 kiloohms
Power supply - 9 volt DC
Here the IR LED is directly connected to the 9 volt DC power supply.As a result the LED glows continuously.The receiver part is designed using an operational amplifier lm356 ic.The op amp amplifies the weak electric signals processed by the photo diode and fed to the output.We use an LED to monitor the output.The potentiometer is used to increase or decrease the sensitivity of the incoming infrared signals.
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