Opto isolated dual relay module (Arduino)

Opto isolated 2 relay module components

This is a dual relay module using the usual Songle SRD-05VDC-SL-C relays.

The module has two spdt relays which can switch:
10A 250V AC
10A 30V DC
Although this would be less for inductive loads.

The module is an active low device, which means that the input must be low to switch the relay on.

The module also contains 817c optocouplers and the input circuit can be isolated from the relay circuit by removing the JD-VCC jumper and providing a separate power supply for the relay.

Arduino 2 Relay Module

Opto isolated 2 relay module connections

The following circuit diagram shows the relay module with the input isolated from the relay.

Arduino 2 Relay Module Isolated// Opto-isolated relay blink sketch

#define RELAY_ON 0			// Define relay on pin state
#define RELAY_OFF 1			// Define relay off pin state

#define Relay  13  			// Arduino pin where the relay connects

void setup()  
  digitalWrite(Relay, RELAY_OFF);      // initialise the relay to off
  pinMode(Relay, OUTPUT);   

void loop() 				// Turn the relay on and off in sequence
  digitalWrite(Relay, RELAY_ON);	// turn the relay on
  delay(1000);               		// wait
  digitalWrite(Relay, RELAY_OFF);	// turn the relay off
  delay(1000);              		// wait

The following photo shows the Arduino Uno running the sketch listed above with the relay wired to two led strips and a 12v battery.

2 relay module arduino led strip


Keyes SR1y Relay module circuit

How does an Electric Relay work?

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