This 2-channel relay module is a compact, Arduino-compatible switching interface designed to let low-voltage controllers safely command higher-voltage or higher-current loads. Each channel uses an electromechanical relay to provide galvanic separation between the control inputs and the switched circuit. The board shown uses two blue Songle-style relays marked SRD-12VDC-SL-C (or equivalent by revision), with a common 10A contact rating printed on the relay case. It is well suited for DIY home automation, test fixtures, lighting control, pump/solenoid switching, and general-purpose power routing where a mechanical relay is preferred.
This 2-channel relay module is a compact, Arduino-compatible switching interface designed to let low-voltage controllers safely command higher-voltage or higher-current loads. Each channel uses an electromechanical relay to provide galvanic separation between the control inputs and the switched circuit. The board shown uses two blue Songle-style relays marked SRD-12VDC-SL-C (or equivalent by revision), with a common 10A contact rating printed on the relay case. It is well suited for DIY home automation, test fixtures, lighting control, pump/solenoid switching, and general-purpose power routing where a mechanical relay is preferred.
The module integrates relay driver stages so a microcontroller pin can control the relay without directly powering the coil. Typical designs include a transistor driver (or driver IC), flyback protection for the coil, and indicator LEDs for power/status. Many versions also include optocouplers on the input side to improve noise immunity when switching inductive loads or when the relay supply is electrically “dirty.” Trigger behavior is commonly selectable as HIGH-level or LOW-level trigger using an onboard jumper block; always confirm the silkscreen labels on your specific board revision (often marked “High/Low level trigger”).
Each relay provides three contact terminals: COM (common), NO (normally open), and NC (normally closed). NO closes to COM when the relay is energized; NC opens from COM when energized. This allows you to implement either “power-on when triggered” (NO) or “power-off when triggered” (NC) behavior without changing firmware logic.
Important: This is a 12V relay module, meaning the relay coils require a 12V DC supply to actuate. The control input logic level and isolation behavior can vary by module revision (for example, whether grounds must be shared depends on how the optocoupler and jumper are wired). For best results, check the board’s input header labels and any included datasheet/schematic.
2-Channel 12V Relay Module Board x1
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