8PCS 5v Relay Module 1 Channel Relay Board for Raspberry Pi with Opto-Isolated High or Low Level Trigger 5v 1 Channel Switch for Arduino

Works great for all sorts of small projects, from Arduino, Pi, and whatever else.

These relay modules seemed to work well. I had to return mine because I needed pins not just screw terminals, but these definitely would have worked for me if I had a ferrule and crimped all those wires at the time. If you are confident working with screw terminals, this is a good relay module as far as I can tell.

I'm using these with ESP32 boards and all is good. I power them off the 5 volt USB feeding through the ESP32 board and the controlling signal is directly from one of the GPIO lines configured as an output. So far in my testing I haven't had any problems with spikes on the power supply lines causing problems for the processor.The one minor thing to be aware of when using a 3.3 volt controller (i.e., an ESP32) is that the relay likely needs to be set up where it's triggered active-high vs. active-low. If you try to use them active-low, the "high" state of the GPIO output may not be high enough to keep from triggering the relay. At least... that's been my experience.

For those complaining about the screws, you probably over tightened them.These are delicate micro electronics - use a proper screw driver that is tiny - this will help greatly.Super easy to use and the zoomed in photos assist with the tiny labeling.

UPDATE May 2024:Using outdoors, even in a covered, sealed box, will not work. I have them in protected cases in a covered garage/shed and they contact weld after about 300 contacts. Eventually, no matter how hard you tap it, the coil will not release. I've been through 20 of them from two orders, all locked up within months. I tried the diode method, did not work so I ordered SOLID state relays at $10 each to replace them.These are FINE for indoors but the slightest amount of heat and/or humidity (even if you protect it in a case like I did) will fuse/weld them within months in my experience with the 20 I had. I have pics and vid but it must be compressed so I'll do that and upload, as promised, as soon as I can get them "uploadable".ORIGINAL POST:These, like many other relays LOCK frequently. Like within 3-500 activations. This means you have to use it in a place where you can tap it gently with something to free it up.How to avoid this ...What is working now for me, is to power the relay completely separate from the Arduino. The only power to the relay is from the activation pin from the Arduino. ALSO ... since I'm deploying these in difficult to reach locations, I've including a flyback diode in the design as well.I have pics & vid on my phone I'll update this with later, once some more testing proves everything operational through a few thousand uses each.

They work well but the terminal screws are not very good. I had to throw a few away.

I used these in combination with a motion sensor in order to trigger my Halloween animatronics. They worked great. Planning on ordering some more later for other props. They were easy to use and so far no problems with them.

Used this combined with a ESP8266 and a temp sensor I am able to control the temps within 2-3 degrees.