SLA-05VDC-SL-C DC 5V 30A Single-Channel optocoupler Isolation Relay Module Supports high and Low Trigger

When looking at the relay with the printing upright: The control portion of the unit is the 4 connectors at the bottom. Connect the 5v power supply to the bottom left, the ground to the top left. Connect the signal ground to the bottom right and the GPIO pin to the top right.In your software (how I did it , anyway) you'll need:import RPi.GPIO as GPIORelayPin = 16 #(You can use which pin number you want except a GND or power pin)GPIO.setwarnings(False)GPIO.setmode(GPIO.BOARD) #(If you use the GPIO number instead on the pin #, ie: GPIO23, change BOARD to BCM)GPIO.setup(RelayPin, GPIO.OUT)When the conditions are met in your program to turn on the relay you'll need:GPIO.output(RelayPin, GPIO.HI) #(turns on the relay)The relay will stay on until the invoke the following:GPIO.output(RelayPin, GPIO.LOW) #(turns off the relay)If you are using the Normally Open side (left and middle connections on the relay itself), turning ON the relay closes the connection completing the circuit.Using the Normally Closed side (middle and right connections on the relay itself), turning ON the relay opens the connection breaking the circuit.YMMV

Purchased these in March and had them installed by May. Controlling 3 winne fridges. Normal operating amps is 7 and starting amps is 25 all at 120VAC. 2 of the 3 the contacts does not work any longer. Worked fine for about 2 months switchin no more than twice a day. One is still working fine. The red light comes on but it does not switch.

working great, but the contacts are a bit small on the A/C side Left a 1 star review earlier, because it just stopped working. But found that the A/C was a problem (ie hard to manage connecting big A/C wires to these small contacts). Once I had them properly fitted the unit has be working fine

I had been using one of the 10A Arduino relay boards to control a baseboard heater that operates at 7.8A @ 240v and both channels ended up fusing shut after a week or two. Bought this one to replace it about a month ago and it has been working great since.

2 of the 3 I ordered failed.I am using these inline with a power cord to switch power on and off. The device I'm powering uses 110VAC and less than 1amp of power.I am using an Arduino Nano to supply voltage and signal to the relay module.The defective relays both fail in the same way. I switch the signal to them, the LED goes on or off based on the signal, but the Relay doesn't physically click or switch. If I tap the relay, it will flip, but without tapping it, it doesn't flip.

Update: They have added some photos with english labels to explain the connections. It works great. So I chsnged from 1 star to 4 stars. It's a good buy.Their is no wiring diagram or instructions for connections and every label on the circuit board is in Chinese. I do not know how to get it working.

Works Great!