This is a 5V 4-channel relay interface board, and each channel needs a 15-20mA driver current. It can be used to control various appliances and equipment with large current. It is equiped with high-current relays that work under AC250V 10A or DC30V 10A. It has a standard interface that can be controlled directly by microcontroller.

Principle

From the picture below, you can see that when the signal port is at low level, the signal light will light up and the optocoupler 817c (it transforms electrical signals by light and can isolate input and output electrical signals) will conduct, and then the transistor will conduct, the relay coil will be electrified, and the normally open contact of the relay will be closed. When the signal port is at high level, the normally closed contact of the relay will be closed. So you can connect and disconnect the load by controlling the level of the control signal port.

Pin Description

Input:

VCC: Positive supply voltage

GND: Ground

IN1--IN4: Relay control port

Output:

Connect a load, DC 30V/10A，AC 250V/10A

Features：

Size: 75mm (Length) * 55mm (Width) * 19.3mm (Height)

Weight: 61g

PCB Color: Blue

There are four fixed screw holes at each corner of the board, easy for install and fix. The diameter of the hole is 3.1mm

High quality Songle relay is used with single pole double throw, a common terminal, a normally open terminal, and a normally closed terminal

Optical coupling isolation, good anti-interference.

Closed at low level with indicator on, released at high level with indicator off

VCC is system power source, and JD_VCC is relay power source. Ship 5V relay by default. Plug jumper cap to use

The maximum output of the relay: DC 30V/10A, AC 250V/10A

Testing Experiment

Experiment Principle

When the input terminals (IN1, IN2, IN3, IN4) are supplied with low level signals, you can see relay K1, K2, K3, K4 closed successively and repeat this cycle. In order to show its the ability of driving load more intuitively, two LEDs are connected to relay K1 and K2.

Code

//the relays connect to

int IN1 = 3;

int IN2 = 4;

int IN3 = 5;

int IN4 = 6;

#define ON 0

#define OFF 1

void setup()

{

relay_init();//initialize the relay

}

void loop() {

relay_SetStatus(ON, OFF, OFF,OFF);//turn on RELAY_1

delay(2000);//delay 2s

relay_SetStatus(OFF, ON, OFF,OFF);//turn on RELAY_2

delay(2000);//delay 2s

relay_SetStatus(OFF, OFF, ON,OFF);//turn on RELAY_3

delay(2000);//delay 2s

relay_SetStatus(OFF, OFF, OFF,ON);//turn on RELAY_3

delay(2000);//delay 2s

}

void relay_init(void)//initialize the relay

{

//set all the relays OUTPUT

pinMode(IN1, OUTPUT);

pinMode(IN2, OUTPUT);

pinMode(IN3, OUTPUT);

pinMode(IN4, OUTPUT);

relay_SetStatus(OFF,OFF,OFF,OFF);//turn off all the relay

}

//set the status of relays

void relay_SetStatus( unsigned char status_1, unsigned char status_2, unsigned char status_3,unsigned char status_4)

{

digitalWrite(IN1, status_1);

digitalWrite(IN2, status_2);

digitalWrite(IN3, status_3);

digitalWrite(IN4, status_4);

}

A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The switch may have any number of contacts in multiple contact forms, such as make contacts, break contacts, or combinations thereof.

Relays are used where it is necessary to control a circuit by an independent low-power signal, or where several circuits must be controlled by one signal. Relays were first used in long-distance telegraph circuits as signal repeaters: they refresh the signal coming in from one circuit by transmitting it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.

The traditional form of a relay uses an electromagnet to close or open the contacts, but other operating principles have been invented, such as in solid-state relays which use semiconductor properties for control without relying on moving parts. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called protective relays.

Latching relays require only a single pulse of control power to operate the switch persistently. Another pulse applied to a second set of control terminals, or a pulse with opposite polarity, resets the switch, while repeated pulses of the same kind have no effects. Magnetic latching relays are useful in applications when interrupted power should not affect the circuits that the relay is controlling.

Latching relay

Latching relay with permanent magnet

A latching relay, also called impulse, bistable, keep, or stay relay, or simply latch, maintains either contact position indefinitely without power applied to the coil. The advantage is that one coil consumes power only for an instant while the relay is being switched, and the relay contacts retain this setting across a power outage. A latching relay allows remote control of building lighting without the hum that may be produced from a continuously (AC) energized coil.

In one mechanism, two opposing coils with an over-center spring or permanent magnet hold the contacts in position after the coil is de-energized. A pulse to one coil turns the relay on, and a pulse to the opposite coil turns the relay off. This type is widely used where control is from simple switches or single-ended outputs of a control system, and such relays are found in avionics and numerous industrial applications.

Another latching type has a remanent core that retains the contacts in the operated position by the remanent magnetism in the core. This type requires a current pulse of opposite polarity to release the contacts. A variation uses a permanent magnet that produces part of the force required to close the contact; the coil supplies sufficient force to move the contact open or closed by aiding or opposing the field of the permanent magnet.[20] A polarity controlled relay needs changeover switches or an H-bridge drive circuit to control it. The relay may be less expensive than other types, but this is partly offset by the increased costs in the external circuit.

In another type, a ratchet relay has a ratchet mechanism that holds the contacts closed after the coil is momentarily energized. A second impulse, in the same or a separate coil, releases the contacts.[20] This type may be found in certain cars, for headlamp dipping and other functions where alternating operation on each switch actuation is needed.

A stepping relay is a specialized kind of multi-way latching relay designed for early automatic telephone exchanges.

An earth-leakage circuit breaker includes a specialized latching relay.

Wrapping Up

Controlling a relay module with the Arduino is as simple as controlling an output – you just need to send HIGH or LOW signals using an Arduino digital pin. With the relay module you can control almost any AC electronics appliances (not just lamps).