1 Channel 5V Relay with led

KEY FEATURES OF RELAY MODULE 5V X 1 RELAY:

• Single relay
• Switch AC up to 125/250VAC @ 10A
• Switch DC up to 15VDC @ 10A
• Normally Open (NO) and Normally Closed (NC) contacts
• LED indicator when relay is energized
• 5V logic compatible

Relay modules are handy for controlling external loads.  Unlike transistors used for switching, relays use metallic switch contacts which avoids the power loss and heating inherent in transistor switching circuits.  They are also  nicely contained little modules that are simple to hook-up and are especially useful for switching AC.  The main downside is that being an electro-mechanical device, like any mechanical switch relays are more prone to wear and tear over prolonged use.

Module Control

These relays are fully 5V logic compatible. The input has a relay driver transistor built-in which means the device only needs about 5mA on the logic control pin to drive it.  If you have a uC like an Arduino, you can drive the relay using any of the digital output pins.

The relay is activated with a logic LOW signal.  There is a green LED that is lit when the control pin is driven low to activate the relay.  When the relay is activated an audible click will be heard.  A logic HIGH deactivates the relay and the LED will go off.

Module Power

The module requires 5V power and Gnd to operate.

At least the ground should be shared with the microcontroller.  There is a red LED that is lit when Vcc is applied to the module.  A flyback diode is included on the module in parallel to the relay coil to safely shunt current when the relay coil is de-energized.

When the relay is energized, the module draws about 80mA from the Vcc pin.

Relay Operation

The output of the relay is rated to switch up to 30VDC at 10A per the relay markings (see our notes below) or up to 125/250VAC at up to 10A.

The output is SPDT type with both a NO (Normally Open) terminal and a NC (Normally Closed) terminal relative to the center unmarked common (COM) terminal.  A logic HIGH energizes the relay, so the NO–COM contact is closed and the NC-COM contact is open.  A logic LOW de-energizes the relay and the NO-COM contact is open and the NC-COM contact is closed.

Note:  Some modules have the relay outputs labeled in Chinese, but the NO/NC connections are the same as shown here.

Module Connections

1 x 3 Header

• GND = Connect to ground of the 5V power supply
• IN1 = Relay control input 1.  Logic LOW level energizes relay 1
• Vcc = Connect to 5V power supply

Relay Contacts

• NC = Normally Closed side of the relay
• Center Terminal = Common terminal usually connects to the load power source
• NO = Normally Open side of the relay