Solenoid Door Lock Circuit with Arduino

In this project we have used Solenoid Door Lock Circuit with Arduino

Solenoid lock works like magnet latch.

Arduino control it using small signal.

With few parts and simple wiring, we can create automatic locking system for our home or office.

Very easy and very useful circuit and is good for DIY security system.

Arduino coding:

int lockPin = 7;

void setup() {
pinMode(lockPin, OUTPUT);
}

void loop() {
digitalWrite(lockPin, HIGH);
delay(3000);
digitalWrite(lockPin, LOW);
delay(3000);
}

Coding Explanation:

• lockPin is the pin that controls solenoid.
• In setup Arduino sets pin as output.
• In loop code turns pin HIGH.
• Solenoid gets power and lock opens.
• Delay waits 3 seconds.
• digitalWrite LOW turns solenoid OFF and lock closes.
• Second delay waits 3 seconds and repeats.

Circuit Working:

Parts List:

Arduino cannot give 12V to solenoid directly.

So we used relay module.

Relay work like electric switch.

Arduino give 5V signal to relay coil.

Relay coil activates and makes the relay click.

When relay clicks, it connects 12V supply to solenoid lock.

Lock pulls inside and door unlocks.

When Arduino sends LOW signal then relay turns OFF.

Relay breaks 12V line.

Solenoid lock loses power and locks back.

So Arduino just controls the relay and relay controls solenoid.

Formula with Calculation:

Formula for solenoid current:

I = V / R

where,

• I is the current
• V is the voltage
• R is the resistance

So, I = V / R means:

Current = Voltage divided by Resistance.

How to Build:

To build a Solenoid Door Lock Circuit with Arduino follow the below connection steps:

• Gather all the parts as shown in circuit diagram.
• Connect Arduino 5V pin to relay module VCC pin.
• Connect Arduino GND pin to relay GND pin.
• Connect Arduino digital pin D7 to relay IN pin.
• Take DC 12V supply positive wire and connect it to relay COM pin.
• Connect relay NO (Normally Open) pin to positive wire of solenoid lock.
• Connect negative wire of solenoid lock to 12V supply negative.
• Connect Arduino to laptop using USB connector for programming.

Conclusion:

This Solenoid Door Lock Circuit with Arduino can safely control a solenoid lock.

Transistor and diode protect Arduino and give proper current to the lock.

Good for door locks, drawers, cabinets and basic home automation.

References:

Solenoid Lock doesn’t work