4Pcs Digital 38khz Ir Receiver Sensor Module + 4Pcs 38khz Ir Transmitter Sensor Module Kit for Electronic Building Block

These are good, cheap IR boards. As other reviewers have noted, the VCC lead on the transmitter isn't actually connected to anything; it's just part of the pin header. The transmitter is just an IR LED and a resistor; the DATA pin is really the + line, so if you send it current there, it turns on. You simply bit-bang on that pin to send pulses. If you're using something like a Raspberry Pi, you won't get great range, because all of the GPIO pins are 3.3 volts. I'm using it to control an A/V receiver and have the LED right next to the panel, so it works great. If you need more range, though, you'll want to hook it up to the 5v rail via a transistor and probably also surround it with an IR reflector (as-packaged, it's an omnidirectional LED).The IR receiver works just like you'd expect, and obviously it _does_ need power, so all three pins are needed: data, vcc (5 volt, although might work with 3.3; I didn't test that), and ground. I believe data is pulled high and drops to ground when a signal is received.If you're using a Raspberry Pi with a reasonably current OS, you don't need to download any drivers; much of what you see online is old. Add the appropriate lines ("dtoverlay=gpio-ir,gpio_pin=" and "dtoverlay=gpio-ir-tx,gpio_pin=") to /boot/config.txt (or /boot/firmware/config.txt if running Debian 12). Note that, if you are going to both send AND receive (i.e. you have both lines in the config file and you've hooked up both boards), you'll need to specify which device to use (--device=) in the ir-ctl command: one will be /dev/lirc0 and the other will be /dev/lirc1; this is why some of the reviewers couldn't do both at the same time.Simply use the 'ir-ctl' command to send and receive pulses. ir-ctl can read to and write from a file, so to train it, just set it to write to a file, and then you can play those exact commands back by reading from the same.

NEW REVIEW, 4/27/21:I'd like to apologize to Dorhea; my initial problem stemmed not from faulty units, but rather misinformation from everywhere else. The reason my units weren't transmitting was because I'd been connecting the signal wire, per literally everyone's instructions, to the wrong pin on my microcontrollers. Once I discovered the proper pin, I retried these transmitters, and they finally not only worked, but performed better than I'd thought they would, with more range than I'd expected. I now fully endorse these products, I fully recommend them, and I hope I haven't turned away too much business.FIRST REVIEW:When you apply these to rebuilds of examples from the handful of tutorials available for this module, no matter how faithfully I've followed said tutorials, these modules just don't work. It's like they can't even power up. What's worse is "DORHEA" is inaccessible for support. I should've known given the lack of reviews or questions. If you're reading this, try a different company, for instance, the equivalent models from Gikfun. In fact, I just bought their IR transmitters. You'll probably have better luck with them.

Since this module has GND, VCC, AND DATA connections I thought it would have some electronics that step up the DATA signal but it does not. I now see the other review that says VCC is not connected which makes this board useless for Arduino/ESP projects. I think Arduino boards provides 40mA and ESP boards only 12-20mA which is way too little to power the DATA connection. You need at least 5V at 1A on the DATA connection to get usable IR range due to the resistors on the module. This REALLY SHOULD BE STATED in the description.I tried using a PN2222 transistor to provide a strong enough DATA signal but it was not enough. So really there is no point in using this module. I could cut of the IR diode and use it directly but that is a waste of money and materials.

I use these on a Raspberry Pi Zero W for a very specific purpose: to monitor if kodi is playing and when it stops playing, turns the TV off (because I have a tendency to fall asleep). My TV doesn't support the power off signal via HDMI, so I had to make something work the old IR way. I did struggle a bit getting it setup, but in the end, I got it.I hooked up the transmitter to 5v and receiver to 3v and used GPIO pins for signal. I couldn't use both receiver and transmitter at the same time, the pi only wants one or the other enabled in /boot/config.txt, but for my purposes that was fine. I loaded the receiver to record the IR signal, then once I had it, I disabled it and enabled the transmitter to send that signal. Good thing to know here: the pin #s it wants are the GPIO numbers, NOT the pin numbers. Once I got that sorted I was good.I can't speak to how well it does with distance, since I have the pi stashed behind the TV and the transmitter sticking out just far enough for the TV to be able to pick it up. Overall I'm happy, the price was good and it works for my need.

The transmitter LEDs are placed backwards, they do not work as soldered. Don’t buy from this seller

Got a bit concerned with the reviews about near zero range on the xmit. I have 6-7 feet (2-2.3M) powered directly from a NodeMCU (ESP8266). It might go further, not sure, that is where my dev desk is in relation to the end point.

The reasons why the transmitter is useless are covered in several other reviews. I was unable to receive accurately when the transmitter was more than 1cm away from the receiver. Attached photo shows optimum working distance of emitter LED to receiver. Fortunately for my application I can get away with this, as I will be taping the emitter to the IR window of my air conditioner. Btw the receiver works fine on the Raspberry Pi using the 5V supply and DATA being connected directly to a GPIO input pin.