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

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.

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 includedwith the device to say what the jumpers on the board do. Also no schematic.So this is why I only gave 3 starts.

Pin labeled Vcc is the ground, and the pin labeled "IN" is the actual Vcc. Pins are mislabeled, zero info about the device provided in package. Would give zero stars if I could.