5Pcs 1 Channel DC 3V/3.3V Power Relay Module 3V Relay Switch Module with Optocoupler Relay Module Isolated Drive Control Board 10A 250VAC 10A 30VDC Control Development Board

I used these connected to an ESP32 dev board running ESPHome to control various buttons in my house through home assistant. For one, I wired the garage door opener button through the relay and I can remotely press the garage door opener button now. For another one, I wired my old analog door bell chime through the relay and I can trigger the doorbell chime through an automation when someone presses the doorbell button on my smart doorbell. What can I say, 3.3v relay is useful when you have 3.3v microcontrollers.

Good value without having to buy more than I need. Worked great for a Raspberry pi project that was controlling 12VDC devices. Quality and workmanship of the board was also very good

Works with 3.3VDC

It’s a basic optoisolator and relay that works with 3.3V just fine. I don’t remember if it came with docs, but the jumper functions are pretty obvious from the board layout and allow isolating the power and ground of the relay from the screw terminals if you want to truly optoisolate the relay coil. Although it is a 250V rated relay you would be crazy to use this for mains power since it is not properly Hi-Pot isolated, but it’s great for a 12-48V solenoid such as a water valve or a small motor.

Very flexible relay circuit. Had search for instructions online.

Versatile boards for hobbyists to drive devices that might use more current than you'd use with a TRIAC. I connected to an ESP32, that combined with input from an air particle sensor, to drive a pool pump connected to misters to spray vinegar whenever my neighbor smokes. Wish it came with instructions or datasheet, but it wasn't overly hard to figure out removing jumpers on the board could be used to isolate DC power for the relay from the screw terminal signal connection.

It’s work perfect and the package value is great. I use is for my motion sensor project. I changed it the signal to the low because my sensor sends negative signal( as you see in picture) but you can also use it with positive signal.

I haven't tried these yet so can't say anything about them. There was no information included with the device to say what the jumpers on the board do. Also no schematic. So this is why I only gave 3 starts.