5V Single Channel RELAY Module

How It Works

A relay is a simple electromagnetic switch.

1. You send a 5V logic signal (HIGH or LOW, depending on the module) to the IN pin from your microcontroller.
2. This signal activates a transistor, which energises an electromagnet (the coil) inside the relay.
3. The magnetic field pulls a mechanical switch, instantly connecting or disconnecting the high-power circuit connected to the screw terminals.
4. Most modules include an optocoupler, which uses light to send the signal, creating a physical gap that electrically isolates your control circuit (microcontroller) from the load circuit (appliance).

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Key Features

• 5V Logic Control: Easily triggered by the digital output pins of most common microcontrollers.
• High-Current Load: Capable of switching loads up to 10A at 250VAC or 10A at 30VDC.
• Optically Isolated: An onboard optocoupler (like the PC817 or EL817) protects your microcontroller from the high-voltage side.
• Status Indicator LEDs: Includes two onboard LEDs:
  • Power LED (Red): Lights up when the module is powered (VCC/GND).
  • Relay Status LED (Green/Blue): Lights up when the relay is active (triggered).
• Secure Screw Terminals: Provides robust and easy-to-use connections for your high-power load wires.
• Freewheeling Diode: Protects your circuit from voltage spikes (back-EMF) generated when the relay coil is de-energised.

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Understanding the Pinout

Low-Voltage Control Side (3 Pins):

• VCC: Connects to the 5V power supply from your microcontroller.
• GND: Connects to the Ground (GND) of your microcontroller.
• IN: The control signal pin. Connects to a digital output pin on your microcontroller.

High-Voltage Load Side (3 Screw Terminals):

• COM (Common): The central pin. This is typically where you connect the “live” wire from your appliance or power source.
• NC (Normally Closed): This contact is connected to COM by default (when the relay is off). The circuit is complete.
• NO (Normally Open): This contact is disconnected from COM by default (when the relay is off). The circuit is broken.

How to use NO/NC:

• To turn a device ON when you trigger the relay (e.g., a light), connect your circuit using COM and NO.
• To turn a device OFF when you trigger the relay, connect your circuit using COM and NC.

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Common Applications

• Home Automation: Control AC lights, fans, and coffee makers.
• IoT Projects: Build smart plugs or web-controlled switches.
• Robotics: Control high-power motors and actuators.
• DIY Projects: Safely switch any high-voltage or high-current device.

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Technical Specifications

• Control Voltage (VCC): 5V DC
• Trigger Current: 15-20mA
• Max Load Rating: 10A 250VAC / 10A 30VDC
• Switching Time: ~10ms
• Module Dimensions: (Typical dimensions, e.g., 43mm x 17mm x 19mm)

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What’s Included

• 1 x 5V Single-Channel Relay Module