Review on SainSmart 101 70 102 8 Channel Relay Module by Lautaro Olive

Some technical knowledge is required for installation. This particular relay uses feedback signals (add "#define ON 0" and "#define OFF 1" to your code, then use ON and OFF to turn devices on and off). Be very careful when setting up the 110v side, you will never need much insulation. This allows me to control up to 8 regular devices that you would normally plug into the wall using my Arduino. My dad showed me how to solder relays to 8 sockets and we installed them in a socket holder we found in our home storage. The device works very well, a loud click and the LEDs on the board indicate that the relay is switched on and off. The relay itself can be powered directly from the Arduino's 5V output.