Relay Module 5V DC 2-Channel

The 2-Channel 5V Relay Module is one of the most popular and widely-used relay boards in the maker and electronics community. It allows your microcontroller, single-board computer, or logic-level circuit to safely switch high-voltage AC or DC loads — such as lights, fans, motors, water valves, heaters, pumps, and small household appliances — using simple digital signals.

This compact module is ideal for projects where you need to control just one or two loads without the bulk and cost of a larger 4, 8, or 16-channel relay board. Its small 41 x 41 x 18.5 mm footprint makes it easy to integrate into enclosures, breadboards, custom PCBs, and tight project spaces — perfect for smart plugs, single-room automation, prototype switches, and dedicated control circuits.

Two Independent Relay Channels

The module features two independent SPDT (Single Pole Double Throw) relays, each providing three connection terminals:

• NC (Normally Closed) — connected to COM when the relay is OFF
• NO (Normally Open) — connected to COM when the relay is ON
• COM (Common) — the pole that switches between NC and NO

This flexible SPDT configuration allows you to:

• Use NO contacts for normally-off loads (most common — load activates when relay activates)
• Use NC contacts for normally-on loads (load deactivates when relay activates)
• Use both NO and NC for selector-style switching (e.g., switch between two devices)

Each channel can switch typical loads up to 10A at 250V AC / 30V DC, making the module suitable for most household appliances, small industrial devices, and DC-powered equipment.

Easy Microcontroller Control

The module is designed for direct connection to microcontroller GPIO pins with a very low trigger requirement:

• Trigger Voltage: 2V – 5V (compatible with both 3.3V logic like Raspberry Pi/ESP32 and 5V logic like Arduino)
• Trigger Current: Only 2 mA — easy to drive from any digital pin
• Logic Level: Active LOW (relay activates when IN pin is pulled to GND)

Each control input is electrically buffered through a transistor stage with onboard pull-up, so the module behaves predictably even when the controlling MCU is in a reset or boot state.

Built-In Indicators

The module includes two types of LED indicators for clear visual feedback:

• Power LED (Green) — confirms the module is properly powered
• Channel Status LEDs (Red) — one per relay, lights when its relay is activated

This makes debugging, testing, and troubleshooting quick and easy — you can immediately see whether your code is correctly switching the relays without needing to test the load circuit.

Robust Construction

The module is built on a high-quality PCB with:

• Quality electromechanical relays (typically SRD-05VDC-SL-C or equivalent) rated for 100,000+ switching cycles
• Heavy-duty screw terminal blocks for secure load wire connections
• Onboard flyback diodes to protect against inductive load spikes
• Standard 0.1" pin headers for easy connection to microcontrollers
• Mounting holes for screw-mounting in enclosures

Universal Compatibility

The module's 3.3V/5V trigger voltage range makes it compatible with virtually all popular microcontroller and SBC platforms:

• Arduino (Uno, Mega, Nano, Leonardo, Pro Mini)
• ESP32 / ESP8266 (NodeMCU, D1 Mini, ESP32 DevKit)
• Raspberry Pi (all models with GPIO)
• STM32 / Blue Pill / Black Pill
• Teensy boards
• PIC and AVR microcontrollers
• PLCs and industrial logic systems

Common Use Cases

This 2-channel relay module is the perfect size for projects that need minimal but flexible switching, such as:

• Smart home single-light controllers (with WiFi via ESP8266/ESP32)
• Kitchen appliance automation — coffee maker + kettle on one module
• Garage door opener — single relay activates the door, second monitors door position
• Aquarium controllers — light + heater
• Bathroom fan + light combo — one module controls both
• Greenhouse mini-automation — fan + water pump
• 3D printer enclosures — light + filter
• DIY smart plugs — one outlet, one indicator
• Robotics power switching — main + auxiliary
• Custom test fixtures with flexible load switching
• Educational STEM projects — first introduction to relay control

Specifications

Module Specifications

• Channels: 2 (independent SPDT relays)
• Operating Voltage: 5V DC
• Static Current (idle): 4 mA
• Working Current (both relays active): 135 mA
• Trigger Voltage: 2V – 5V (3.3V and 5V logic compatible)
• Trigger Current: 2 mA per channel
• Activation Logic: Active LOW (typical)
• Module Dimensions: 41 x 41 x 18.5 mm

Relay Specifications (Typical for Standard Modules)

• Relay Type: SPDT (Single Pole Double Throw) Electromechanical
• Maximum Switching Current: 10A
• Maximum AC Voltage: 250V AC
• Maximum DC Voltage: 30V DC
• Operation Cycles: 100,000+ (typical)
• Switching Time: ~10 ms

Indicators

• Power LED: 1 (Green)
• Channel Status LEDs: 2 (Red — one per relay)

Pinout

Module Interface:

Relay Outputs:

Applications

Home Automation

• Smart light switches — single or dual lighting control
• Dual-outlet smart plug — independent control of two outlets
• HVAC control — fan + heater combination
• Garage door + door sensor
• Outdoor lighting — pathway + security light

Smart Appliances

• Coffee machine + grinder — automated morning routine
• Aquarium light + heater
• Pet feeder + lighting
• Plant grow lights + watering pump

Industrial & Commercial

• Small motor control (with proper interface)
• Solenoid valve actuation — water, gas, pneumatic
• Indicator lamp panels
• Conveyor on/off + alarm
• Test equipment switching
• Lab equipment automation

Robotics & Maker Projects

• DC motor reversing circuits (using both NO and NC contacts)
• Power switching for high-current modules
• Battery management — switching between battery and charger
• Educational STEM projects
• DIY smart switches
• Hackathon projects

Security & Access

• Door strike control (one channel) + alarm beacon (second channel)
• Magnetic lock + intercom buzzer
• Surveillance camera power + IR illuminator
• Driveway gate + warning light

IoT & Smart Devices

• WiFi-controlled smart switches (ESP8266/ESP32)
• Voice-controlled appliances (Alexa, Google Home, Siri)
• MQTT-controlled remote switches
• LoRa / NB-IoT remote actuators
• Cloud-controlled industrial devices