2-Channel Relay Board Module, Active-Low

A relay is an electrically operated device. It has a control system and (also called input circuit or input contactor) and controlled system (also called output circuit or output contactor). It is frequently used in an automatic control circuit. To put it simply, it is an automatic switch to controlling a high-current circuit with a low-current signal.

The advantages of a relay lie in its lower inertia of the moving, stability, long-term reliability and small volume. It is widely adopted in devices of power protection, automation technology, sport, remote control, reconnaissance, and communication, as well as in devices of electromechanics and power electronics. Generally speaking, a relay contains an induction part which can reflect input variable like current, voltage, power, resistance, frequency, temperature, pressure, speed and light etc. It also contains an actuator module (output) which can energize or de-energize the connection of controlled circuit. There is an intermediary part between input part and an output part that is used to coupling and isolate input current, as well as actuate the output. When the rated value of the input (voltage, current and temperature etc.) is above the critical value, the controlled output circuit of the relay will be energized or de-energized.

Features

• SMD optocoupler isolation
• Good in safety. In power system and high voltage system, the lower current can control the higher one, able to control various appliances and other equipment with high-current current.
• Standard interface that can be controlled directly by microcontroller (Arduino, 8051, AVR, PIC, DSP, ARM, ARM, MSP430, TTL logic).
• Indication LEDs for Relay output status.
• With a normally-open (NO) and a normally-close (NC) contact.

Specification

• Number of Relays: 2
• Working voltage: Optional 5V / 12V / 24V DC
• Control signal: TTL level
  • 5V Relay:   0 – 2V: Turn-ON relay;    3 – 5V: Turn-OFF relay
  • 12V Relay:   0 – 4V: Turn-ON relay;    5 – 12V: Turn-OFF relay
  • 24V Relay:   0 – 8V: Turn-ON relay;    9 – 24V: Turn-OFF relay
• Rated load: 7A/250VAC; 10A/125VAC; 10A/28VDC;
• Contact action time: 10ms / 5ms
• Current: 
  • 5V Relay: 52mA± per channel
  • 12V Relay: 32mA± per channel
  • 24V Relay: 20mA± per channel

The Connections (Example for 1 channel relay module)

Arduino Sketch

void setup(){
   pinMode(7,OUTPUT);
}
void loop() {
   digitalWrite(7, HIGH);
   delay(4000);
   digitalWrite(7,LOW);
   delay(2000);
}