Embarking on your first Arduino project can be both exciting and a little daunting, especially when it involves hardware configurations. Many beginners, even with programming experience, find themselves navigating the physical connections and power requirements of electronic components. Let’s explore a common beginner project: building a fingerprint scanner-activated electric door strike. This project nicely illustrates how a car scanner can operate devices relays solenoids actuators, albeit in a different context, by using an Arduino to control an electric strike based on fingerprint authentication.
For this project, a fingerprint scanner module with readily available Arduino code is a great starting point. Connecting this to an electric strike allows you to create a secure and keyless entry system. However, understanding the electrical configuration of the electric strike is crucial.
Electric strikes typically operate by receiving a constant power supply. To release the lock, this power supply needs to be interrupted momentarily. Consider the electric door strike designed for Schlage locks, operating at 8-12VDC, paired with a 12-Volt DC power supply. These strikes usually have two wires. One wire connects to the power supply, completing the electrical circuit, while the other is part of the circuit that needs to be controlled to activate or deactivate the strike. It’s important to refer to the product’s documentation to confirm wire designations, although many are designed for straightforward wiring.
Initially, you might consider directly connecting the electric strike to the Arduino. However, Arduino operates at a low voltage (typically 5V or 3.3V) and cannot directly handle the higher current and voltage requirements of an electric strike (12V in this example). This is where a relay becomes essential. A relay acts as an electrically operated switch. The Arduino can control the relay using its low voltage output, and the relay, in turn, can switch the higher voltage circuit for the electric strike.
To visualize the wiring, consider a common setup involving a transistor to control a motor. In this scenario, you would replace the motor with the electric strike and omit the potentiometer if not needed for your project. This kind of diagram illustrates the fundamental principle: the Arduino controls a switch (transistor/relay) which then manages the power to the higher voltage device (motor/electric strike).
In the context of car scanners, they also operate various devices, relays, solenoids, and actuators within a vehicle. While a car scanner is a diagnostic tool, the underlying principle of using electronic signals to control electrical devices is similar to what we’re doing with the Arduino and electric strike. Both scenarios involve using a low-power control signal to manage higher-power electrical components. In our door lock project, the Arduino, acting somewhat like a simplified control unit, uses a relay (an electrically controlled switch) to operate the electric strike (an actuator, specifically a solenoid-based actuator).
Therefore, to correctly wire the electric strike, you would connect one wire of the strike to the 12V power supply. The other wire would connect to one side of the relay’s switch contacts. The other side of the relay’s switch contacts would then go back to the power supply, completing the 12V circuit through the electric strike. The relay coil itself is controlled by the Arduino. When the Arduino signals the relay (after successful fingerprint scan), the relay closes (or opens, depending on relay type and wiring), interrupting the power to the electric strike and releasing the lock.
Understanding these basic principles of electronic control, especially the role of relays in interfacing low-power microcontrollers with higher-power devices like electric strikes, is fundamental in DIY electronics projects. As you progress, you’ll find these concepts applicable across a wide range of applications, from home automation to even understanding the basics of how systems in a car, controlled by something like a car scanner, function. Don’t hesitate to experiment and ask questions – every expert started as a beginner!
