4-Channel 5V Relay Shield for Arduino UNO

This 4-channel 5V relay expansion shield plugs directly onto an Arduino UNO or compatible development board without the need for patch cables. It allows low-voltage microcontroller logic to switch higher-power external equipment. It is ideal for learners, makers, and hobbyists building automated switching and smart home projects.

Direct stacking design

Built to the standard Arduino shield footprint, this board mounts directly onto your Arduino UNO and allows additional expansion shields to be stacked on top.

Independent relay channels

The module features four HJR-4102-L-5V 5V DC relays triggered by a 5V or 3.3V high-drive signal, with dedicated red indicator LEDs that illuminate when each relay is activated.

Terminal switching contacts

Each channel includes screw terminals for normally open (NO), normally closed (NC), and common (COM) connections for wiring external electrical loads.

Mounting and safety notice

The board includes three M3 screw positioning holes for secure installation. When fitting to an Arduino UNO, ensure the terminal block underside does not short against the USB interface shell.