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Friday, December 9, 2011

IR Transmission..what u use in remotes...

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Hi everyone.Hope u r enjoying the days.After so many days  I m back & posting a communication protocol which is mostly used in ur remote controller of TV,AC & laptop…
So u need to know about certain things about Infra Red Communication

(1). IR(Infra red) : Like light rays IR is also a type of ray. But since it has longer wavelength than visible light, we can't see thm with our eyes. It has mny applications like thermal Imaging, IR communication etc.

(2). Photodiode : A photodiode is like a simple diode, but the main difference is that the reverse resistance of a photodiode changes with respect to intensity of light falling on it. Thus we can say that resistance of a photodiode in reverse bias depended on the light falling on it. But the characteristic of a photodiode which I have used  in this ckt  is that photodiode's resistance also changes when IR(Infra red) rays fall on it. Thus I have used photodiode as a detector to detect IR rays in this prjct.

(3). IR LED : It is same as a simple LED but it emits IR rays  rather than  light. The intensity of IR rays depend on the voltage apled to it.
ckt diagram for the making of ir detector
Lets learn about the wireless communication ,I think it is new to all of u…
Do the ckt in lab once thn u will be clear about it…
Any wireless communication system has three important parts.
1. Transmitter
2. Receiver
3. Transmission Medium

1. Transmitter : In this project I have used a simple IR LED to transmit IR rays. I have given input signal(It can be any type of electrical signal. I used sine wave of 5v amplitude) to battery and then to IR LED. Thus IR LED will emit IR rays whose frequency is same as frequency of input signal & its intensity depends on amplitude of the i/p signal.

2. Receiver : As I have mentioned above, a photodiode's resistance changes when IR rays fall on it. Thus we can use photodiode as a IR detector. I have applied reverse biasing to photodiode & connected a 500 ohm resistor. Now when IR rays fall on photodiode, its resistance changes,depending on the intensity of IR rays falling on it. So the current through the 500 ohm resistor changes. Thus this circuit acts as a IR detector.

3. Transmission Medium : It is clear that this circuit uses IR rays as a transmission medium.

Now when the receiver is given any sort of electric signal & IR LED is placed in front of photodiode the same signal as applied to receiver is produced accross the 500 ohm resistor. We can see the output with the help of a C.R.O.

This LED & Photodiode we can use for detection for different colour surface ,we can use it for line follower ,obstacle detector & many projects…


Pls give ur feedback regarding this post,ur comment will be helpful in improving myself…mail me sachi059@gmail.com
Bye Hv a nice day…
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