4 Channel 5V Relay Module 10AMP/250V

If you love to play with Arduino Boards, and like to expand your Arduino projects into more real-life applications rather than just low voltage hobbyist projects, this 4 Channel 5V Relay Module rated at 10A/250V AC or 10A/30V DC is the perfect module for you. Operating on a low voltage of 5V DC so as to accommodate the standard 5V supply on many different microcontrollers, this relay module offers four controllable and isolated relays that can be integrated into high voltage circuitry, allowing you to control various Electronics and appliances from a simple Arduino board by switching the IN pin between HIGH and LOW state.

In addition to nice quality components and individual circuits for each relay, this module also offers a clever safety feature. When the relay is connected via the NO and COM contact terminals, the corresponding digital pin IN must be set to LOW to close the circuit and allow power through. This ensures that even if your Arduino turns off for some reason, the NO contact will still stay closed. Conversely, if you want to stop power flowing through the relay, you need to set the corresponding IN pin to HIGH, which of course opens the circuit to cut power flow.