4 Channel 5V Relay Module with Optocoupler Isolation (10A)

This 4-channel relay board is designed to interface a microcontroller or control logic running at 5 V with four separate external loads. Each channel is isolated via an optocoupler on the input side to protect the control logic from noise, voltage spikes or ground-loop interference caused by the switching of inductive or high-power loads.

The relays on the board are standard 5 V coil relays (for example SRD-05VDC-SL-C or equivalent), rated for switching currents up to 10 A at AC or DC voltages. Each channel has its own screw-terminal connector for Common (COM), Normally-Open (NO) and Normally-Closed (NC) connection, and a status LED indicating when a relay is activated.

The input side accepts 5 V trigger signals (TTL / CMOS). Some versions may support configurable high-level or low-level triggering via jumper setting. Mounting holes are provided on the PCB for secure installation. This board is useful in home automation, IoT control, robotics, embedded systems, and general-purpose switching applications where multiple independent outputs are needed.