9V 2-Channel Relay Module, Dual Relay Switch Board with Optocoupler Isolation, High/Low Level Trigger for Arduino DIY Control

This 9V 2-Channel Relay Module is a practical switching solution for electronics projects that need to control higher-voltage or higher-current devices using low-voltage signals from a microcontroller. It includes two independent relays on one board, allowing you to control two separate circuits—ideal for smart home prototypes, automation panels, robotics power switching, lighting control, and general DIY electronics.

The module is commonly used as an interface between a controller (Arduino, ESP32, STM32, Raspberry Pi GPIO via suitable signal level) and real-world loads such as lamps, small pumps, solenoids, fans, DC loads, or AC appliances (within relay ratings). Each relay provides three terminals: COM (common), NO (normally open), and NC (normally closed). This lets you choose default-off or default-on behavior depending on how you wire the load.

Many versions of this board include optocoupler isolation and transistor driver circuitry, which helps the control signal remain stable and reduces the impact of electrical noise generated by inductive loads. Indicator LEDs are usually present to show power and channel switching status, making it easier to troubleshoot during installation and testing.

This module is powered separately (9V input for the relay board). The input pins accept control signals from a microcontroller or logic source. Depending on the board design, it may support high-level or low-level triggering (sometimes selectable). Always verify your specific board’s labeling and logic before connecting.

Common applications

• Home automation: lights, sockets, small appliances (within relay rating)
• Robotics: switching motors, pumps, solenoids, power rails
• IoT projects: remote switching using ESP32/Wi-Fi modules
• Safety interlocks: enabling/disabling circuits using NC/NO wiring
• Test benches: quick switching for prototypes and experiments

Safety and usage notes

• Always confirm relay contact ratings printed on the relay case and keep within limits.
• For AC mains wiring, use proper insulation, enclosure, and safety practices.
• Inductive loads (motors/solenoids) may require snubber/diode protection depending on your wiring.
• Ensure controller ground reference and input wiring match the board’s trigger requirements.

Specifications

• Product Type: 2-channel relay module (dual relay switch board)
• Module Supply Voltage: 9V DC (relay board power)
• Channels: 2 independent relays
• Trigger Input: IN1 / IN2 control inputs (high/low level trigger depends on model)
• Output Terminals: COM / NO / NC per channel (screw terminals)
• Interface: TTL logic control (use proper level shifting if required)
• Indicators: Power LED and relay status LEDs (typical)
• Isolation/Driver: Optocoupler + transistor driver stage (typical, depends on board version)
• Mounting: PCB mounting holes for fixed installation
• Compatibility: Arduino & Compatible, ESP32, STM32, Raspberry Pi GPIO (with correct logic levels)

This 9V dual relay module is a reliable choice when you need simple, affordable switching control in DIY electronics and automation projects—especially when you want two channels in one compact board.

Included Components
9V 2-channel relay module board