Automatic on off fan and light codevisionavr

Here is how you can distinguish between IR TX-RX using DMM : In case you will have to take help of multimeter to distinguish between them. However you may come across pairs which appear exactly same or even has opposite colours than shown in above pic and it is not possible to distinguish between TX and RX visually. Following snap shows 3mm and 5mm IR pairs.Р”В¬olour of IR transmitter (IR-TX) and receiver (IR-RX) is different. It can be obtained from any decent electronics component shop and costs less than 10Rs. This infrared transmitter and receiver is called as IR TX-RX pair. IR sensor is nothing but a diode, which is sensitive for infrared radiation. 3mm is better as it is requires less space. IR LED is used as a source of infrared rays. Alternatively, you can use on-chip ADC in AVR microcontroller to measure this voltage and perform comparison in software. This voltage can then be given to OPAMP based comparator.Output of the comparator can be read by uC. Thus as intensity of incident rays varies, voltage across resistor will vary accordingly. This current can be passed through a resistor so as to get proportional voltage. More intense radiation results in more reverse leakage current. Amount of electron-hole pairs generated depends on intensity of incident IR radiation. When photons are incident on reverse biased junction of this diode, electron-hole pairs are generated, which results in reverse leakage current. This reflected light is made incident on reverse biased IR sensor. Depending on reflectivity of the surface, amount of light reflected varies. This radiation illuminates the surface in front of LED.

If you want to make more reliable, sensitivity adjustable, IR sensor modules checkout the new tutorial here РІР‚вЂњ DIY Infrared Sensor Module.

Automatic on off fan and light codevisionavr