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.

These ir modules are great, I like the led indicator, displays it codes being revived and sent, these will be very useful for my iot projects!

Lacks power! As it turns out, the Vcc pin on the transmitter is a dummy, not actually tied to anything. All the current that reaches the IR LED is also driving the resistor/indicator LED combo too. That makes no sense to me. Why would they do that? They could have lowered their production costs (only a 2-pin header), reduced the size, and given the user a heads-up as to what they were getting.

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

This is my bad, but transmitter is so bad - the range of this module is less than 1 meter. Don’t know why you need that. Receiver works fine so 3 stars :)

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.