IR sensor

[vick5821]

Based on this tutorial :
http://tutorial.cytron.com.my/2012/09/0 ... ir-sensor/


For the receiver, when it receive the IR sensor light the resistance value of itself will drop, on the other way when the IR receiver did not receive any IR the internal resistance value it high.

Is this the properties of the receiver ?

So, when the resistance value drop, the voltage will decrease, mean the resister on top of it accumulate more voltage in that region, so the LED will light on. It is the same at the other way round.

Why when accumulate more voltage it will light on the LED ? Higher difference in potential between the two point that cause the current to flow through the LED ? Am I correct ?

By the way, how if I plan to interface this with arduino UNO ?

Thank you

[yonghui]

when the receiver is shined by IR, the resistance over the receiver drop. according to voltage divider law, the voltage across the receiver will drop also. this make the voltage across the resistor and LED rise, since the total voltage maintained same,5V. so the LED will light up.
for the circuit shown, with the LED, u can connect to arduino Analog pin and read the analog value. else u can add a comparator, LM324, or MCP601,MCP602 to convert it to digital value, and connect to digital pin of arduino.

[vick5821]

Okay. Get it. So this kind of receiver LED is different with 3 pins receiver phototransistor ? The working principle is different ?

[sich]

I take the 3-pin thingy you mentioned as IR receiver used in those TV remotes. Usually It looks like this:

It is different compared to the one in your link. This 3-pin IR receiver has filtering and 38kHz demodulation built into the unit. So it's mainly for IR remote application.

[yonghui]

im not so sure which kind of phototransistor u mentioned. if its the type SiCH, then its a module which contains the filter, and the transmiter will need to modulate the signal will the frequency of the device.

another type with 3 legs, not much different, just that it has better gain.

which type u are using?

[vick5821]

I bought this : http://www.cytron.com.my/viewProduct.ph ... trol%20Kit

Is this different from the 2 pin transmitter and receiver ?

[yonghui]

oh, thats what mentioned by Sich.

so u can get the sample code of Arduino from the product page.

the remote sends modulated signal data out and the receive will receive the signal. and it has daylight filtering which eliminates noises of environment light