IR Send and receive

All fixed :slight_smile:

Your IR receiver should look something like one of these 3 pin devices:



Thank you for your reply. My receiver does look like that, I had a little not saying that the LEDs were not LEDs. I have a plan you see. I want to do it using visible light and the IR was for testing only. However the IR wasn't working either. Problem was the signal was too small. Now for the really difficult bit - to get it working with VLC :confused:

Thanks again


Great that it is fixed. But you edited the first post in a way that nobody in future will be able to follow the logic of the thread and learn from it.

Question to the experts:
Can somebody suggest a (safe?) way of figuring out the pins of unknown IR receivers?

I've got an assortment of such receivers, 2 or 3 of each type. It won't really harm if one or more are damaged by the test, but perhaps there exists a simple non-destructive procedure?

ATM I cannot provide pictures, but when I found out more I'll try to extend your great sample zoo.

As you are aware the power supply pins are going to be the problem.
Maybe add some resistance in series with the power pin to prevent smoke.

Look at the image I posted, maybe you can identify the right part.

However, these are so inexpensive, throw yours away and buy a bunch from eBay.
I like it using the NEC protocol and find the TSOP4338 an excellent part.


Perhaps a version like this:


Some experiments revealed that all tested IR receivers have a resistor between signal and +. This resistor can be found using an ohmmeter, showing the same value (10-100k) in both directions. Then the remaining pin is -, with a very high resistance to the other pins.

For the distinction of signal and + I couldn't find a simple test, the DC currents are almost the same when connected to +3.3 or 5V. Also the other pin stays at about + level, caused by the resistor. Only when the remote control sends some code, the signal output shows pulses to - on a scope or other test device.

All my receivers worked on both 3.3V and 5V supply voltages. No receiver broke when power was applied to the wrong pin :slight_smile:

No guarantee whatsoever, perhaps somebody wants to confirm my findings?