Situation: I was trying to make a simple Arduino program that mimics my TV-Remote ON-OFF button.

Diagnosis: It just won't work. So just to check I grabbed another Arduino (2) and added my IR-Sensor to that one and let it look for the signals sent by Arduino (1).

Conclusion: Even though I ran exactly the same program in a loop sending IR signals, Arduino (2) noticed each time another IR signal. The received signals didn't even look like the IR signal I sent.

The way I connected my IR-LED (By Adafruit)

The program I use to mimic my remote: Link to the Github. It is an example of a Lib

It could be the LED. Just a LED I picked up without being specific. Link to the Documentation of the LED

  • You should use an oscilloscope or logic analyzer to examine what you are actually sending from your program and compare that with what you think you are sending.
    – Majenko
    Commented Oct 21, 2017 at 11:05

1 Answer 1


Sorry not enough rep to comment. Had to answer instead.

So if your schematic is correct then you just fried your LED. You need a series resistor between vcc and the LED.

If it's not accurate and you have the resistor in place, I'd check the LED anyway, it could be a dud. Apply voltage with a resistor and look at it with your cell/mobile phone digital camera, you should see it through the camera glow dimly.

If all is good then it might be the wavelength of the LED, which is 850nm. Most IR LED's I've used are 950nm, actually they all were.

Now I don't know what the specs of your receiver are but it might be out of its sensing (is that a word?) range, also it only has a 20° viewing angle, so check the alignment of transmitter and receiver.

I'm also confused by your statement that your getting signals that don't look like IR. This makes me wonder if your sensor is hooked up properly. It could be background IR or from another source. Look around the room or test elsewhere.

  • My answer assumes there is no issue with the sketch. Could you post your sketch. How did you verify that the Arduino/IR LED actually sent a signal?
    – Tibsy
    Commented Oct 24, 2017 at 15:44
  • I will upload my sketch when I get home. I did check if it glows with my phone, and it does. "How did you verify that the Arduino/IR LED actually sent a signal?" I used my phone for that and another arduino which has a IR reciever. (I know for sure that the reciever is working because I made lots of consistent recordings of my TV-remote. :) Commented Oct 25, 2017 at 12:05

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