Arduino Nano - Solenoid Lock

This tutorial instructs you how to use Arduino Nano to control the solenoid lock, which is also referred to as the electric strike lock. We can apply this secure cabinets, drawers, and doors.

Hardware Preparation

1	×	Official Arduino Nano
1	×	Alternatively, DIYables Nano V3.0 Development Board
1	×	USB A to Mini-B USB cable
1	×	Solenoid Lock
1	×	Relay
1	×	12V Power Adapter
1	×	DC Power Jack
1	×	Recommended: Screw Terminal Expansion Board for Arduino Nano
1	×	Recommended: Breakout Expansion Board for Arduino Nano
1	×	Recommended: Power Splitter for Arduino Nano

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of Solenoid Lock

The Solenoid Lock Pinout

The Solenoid Lock has two wires:

The Positive (+) wire (red) must be connected to the 12V of the DC power supply
The Negative (-) wire (black) must be connected to the GND of the DC power supply

How It Works

When the Solenoid Lock is powered, the lock tongue is extended and the door is locked.
When the Solenoid Lock is NOT powered, the lock tongue is retracted and the door is unlocked.

※ NOTE THAT:

The solenoid lock typically requires 12V, 24V or 48V power supply. Consequently, it CANNOT be connected directly to an Arduino Nano pin. A relay must be used to connect it to the Arduino Nano pin.

If we link the solenoid lock to a relay (in the normally open mode):

When the relay is not activated, the door is unlocked
When the relay is activated, the door is locked

Connecting Arduino Nano to a relay allows us to program it to control the solenoid lock. To learn more about relays, please refer to the Arduino Nano - Relay tutorial.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Nano Code

The code below will cause the door to be locked and unlocked every five seconds.

Detailed Instructions

Copy the code and open it with Arduino IDE.
Click the Upload button on Arduino IDE to compile and upload the code to Arduino Nano.
Check out the lock tongue's condition.

Arduino Nano - Button Controls Solenoid Lock

Diagram of Wiring

This image is created using Fritzing. Click to enlarge image

See The best way to supply power to the Arduino Nano and other components.

Writing code for an Arduino Nano board.

/* * This Arduino Nano code was developed by newbiely.com * * This Arduino Nano code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano/arduino-nano-solenoid-lock */ #include <ezButton.h> #define BUTTON_PIN 8 // The Arduino Nano pin connected to button's pin #define RELAY_PIN 2 // The Arduino Nano pin connected to relay's pin ezButton button(BUTTON_PIN); // create ezButton object for pin 12; void setup() { Serial.begin(9600); // Initialize the Serial to communicate with the Serial Monitor. pinMode(RELAY_PIN, OUTPUT); // set arduino pin to output mode button.setDebounceTime(50); // set debounce time to 50 milliseconds digitalWrite(RELAY_PIN, HIGH); // lock the door } void loop() { button.loop(); // MUST call the loop() function first if(button.isPressed()) { Serial.println("The button is pressed"); digitalWrite(RELAY_PIN, LOW); // unlock the door in 10 seconds delay(10000); // 10 seconds digitalWrite(RELAY_PIN, HIGH); // lock the door again } }

Detailed Instructions

Install the ezButton library. Refer to How To for instructions.
Copy the code and open it with the Arduino IDE.
Click the Upload button on the Arduino IDE to upload the code to the Arduino Nano.
Push the button once.
Check out the lock tongue's state over 10 seconds.

※ NOTE THAT:

In the code above, we utilized the delay function. Thus, no debouncing for the button is necessary. Nevertheless, we still included the code with debouncing in the event that you would like to perform additional tasks without making use of the delay function. For more information, please refer to How to use millis() instead of delay().

Relay vs MOSFET Module for the Solenoid Lock

This tutorial uses a relay to switch the solenoid lock. A 12V solenoid lock runs on DC, so a MOSFET module can also switch it.

	Relay	MOSFET Module
Lock control	lock or unlock	lock or unlock
Switching sound	a click every time	no sound
Switching time	slow (milliseconds)	very fast
Wear	the contacts get old with use	no moving parts to wear
Works with	AC and DC locks	DC locks only
Flyback diode	most relay modules do not need one	must add one (1N4007 or 1N5819)
Isolation	yes	yes, with a PC817 optocoupler
Choose it for	a simple, common setup	a silent lock, or a door that opens many times a day

A solenoid lock is only locked or unlocked, so the MOSFET module does not give extra control here. Its gains are: no click, and nothing wears out. Both turn on when the pin is HIGH, so the code stays the same. Do not keep the lock unlocked for a long time, or it gets hot. This is the same with a relay.

A solenoid valve works the same way as a solenoid lock. To see how to wire and code one with both a relay and a MOSFET module, see the Arduino Nano - Water/Liquid Valve tutorial. The wiring for a solenoid lock is in the Arduino Nano - MOSFET Module tutorial.

Video Tutorial

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