The LM7805 is a popular voltage regulator integrated circuit (IC) that provides a stable 5V output from a higher voltage input, typically ranging from 7V to 35V. This makes it an essential component for powering Arduino projects, which often require a steady 5V supply for optimal performance. In this article, we will explore the importance of the LM7805, how to integrate it into your Arduino projects, and provide a detailed example project.

Project:

Our example project will involve creating a simple 5V power supply for an Arduino Uno using the LM7805 voltage regulator. The objective is to demonstrate how to use the LM7805 to ensure a stable 5V power source, which is crucial for the reliable operation of the Arduino and its peripherals. This project will include:

• Setting up the LM7805 with appropriate capacitors for smooth voltage regulation.
• Connecting the LM7805 to an Arduino Uno.
• Verifying the output voltage using a multimeter.

Components List:

• 1 x LM7805 Voltage Regulator IC
• 2 x 10µF Electrolytic Capacitors
• 1 x 0.1µF Ceramic Capacitor
• 1 x Arduino Uno
• 1 x Breadboard
• Jumper wires
• 1 x Multimeter (for verification)

Examples:

1. Setting Up the LM7805:

   • Place the LM7805 on the breadboard.
   • Connect the input pin (pin 1) of the LM7805 to the positive terminal of your power source (e.g., a 9V battery).
   • Connect the ground pin (pin 2) of the LM7805 to the negative terminal of your power source.
   • Connect a 10µF electrolytic capacitor between the input pin and ground to stabilize the input voltage.
   • Connect another 10µF electrolytic capacitor between the output pin (pin 3) and ground to stabilize the output voltage.
   • Optionally, add a 0.1µF ceramic capacitor in parallel with the output capacitor for better noise filtering.

2. Connecting to Arduino:

   • Connect the output pin of the LM7805 to the 5V pin of the Arduino Uno.
   • Connect the ground pin of the LM7805 to the GND pin of the Arduino Uno.

3. Verifying the Output:

   • Use a multimeter to measure the voltage between the output pin of the LM7805 and ground. It should read approximately 5V.
   • Once verified, power the Arduino Uno using the regulated 5V output from the LM7805.

Here is a simple code example to verify that the Arduino is powered correctly and running:

// Simple Blink Example to verify Arduino is powered
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

Explanation:

• pinMode(LED_BUILTIN, OUTPUT); sets the built-in LED pin as an output.
• digitalWrite(LED_BUILTIN, HIGH); turns the LED on.
• delay(1000); waits for one second.
• digitalWrite(LED_BUILTIN, LOW); turns the LED off.
• delay(1000); waits for another second.

This simple blink code will help you confirm that the Arduino is receiving power from the LM7805 and operating correctly.