Blinking Two LED

Blinking Two LED
Blinking Two LED

You’ve heard about blinking LED projects and wondered how hard they are to construct. It’s simpler than you think! You can blink LEDs quickly with an Arduino, LEDs, and resistors. This article demonstrates a simple circuit to flash two LEDs. No electronics expertise required! I’ll describe each component’s function and breadboarding. You’ll soon have a blinking LED creation. Watching the LED blink for the first time is worth the effort. Let’s start your first blinking LED project!

Understanding LED Basics
What’s LED?

A semiconductor device called an LED emits light when electric current runs through it. LEDs outlast incandescent lamps and are more efficient. Their colors include red, blue, and green.

How LEDs Work

A chip with anodes and cathodes makes up LEDs. Anodes are positive and cathodes are negative. Electrons flow from cathode to anode when linked to power. This electron flow is current, measured in amps.

Photons are released by electrons in semiconductor material. Semiconductor energy bandgap determines light hue. Smaller bandgaps emit yellow or red light, while bigger ones emit blue light.

Polarity Matters

Only one direction of current flows through LEDs. LEDs don’t light up when connected backwards. Connect the anode (positive side) to the power supply’s positive terminal and the cathode (negative side) to the negative terminal. Backward installation prevents current flow and LED illumination. To operate LEDs, they need a particular amount of current, measured in milliamps (mA). Without a resistor, too much current can destroy the LED. Adding ohms (Ω) resistors to LED circuits controls current flow.

Standard LEDs typically need 10-20 mA. Calculate the resistor value using Ohm’s law and the LED’s recommended current and power supply voltage. For a 5V power source and 15 mA LED, a 330Ω resistor is suitable. Building simple LED circuits requires understanding LED principles like light production, polarity, and current limiting with resistors. A few simple components will blink LEDs in no time!

Essentials for LED Blinking

A few simple components make an LED blink. Light-emitting diodes (LEDs) are miniature electronic lights that run on low voltage. A basic LED blinking circuit requires an LED, resistor, battery, and switch.

The LED Light

Start with a 5mm LED light. One LED leg is longer. The positive anode is longer and the negative cathode shorter. This project requires a red, yellow, or green LED.


Obtain a 470-ohm resistor. The resistor restricts LED current to prevent burning. One end of the resistor goes to the LED anode and the other to the battery positive terminal.

Use a 3-volt battery to power the circuit. One CR2032 coin cell battery or two 1.5-volt AA batteries will do. Positive and negative battery ends connect to the resistor and switch, respectively.


Finally, install a small toggle switch for on/off. The switch toggles the LED on and off depending on circuit completion. Connect one switch terminal to the battery’s negative end and the other to the LED’s cathode.

Your LED should blink on and off when the switch is closed and open with these components in a circuit. Try different resistors and batteries to blink the LED faster or slower. Your blinking LED circuit will be working soon!

Building a Blinking LED Circuit

LED flickering requires a microcontroller such an Arduino Uno. Uno digital pins can power components with 5V (HIGH) or 0V (LOW). Programming the Uno to cycle its pin between HIGH and LOW at a specified interval makes an LED flicker on and off.

Get Your Parts
Beyond the Uno and LED, you’ll need:

A 220 ohm resistor to reduce LED current.

Breadboard for circuit construction.

Jumper wires join.

Build Circuit

Place Uno, breadboard, LED, and resistor on your work surface. Connect components as follows:

The LED’s positive leg should be connected to a jumper wire. One resistor end is connected to the negative leg.

The resistor’s other end should be connected to the Uno’s GND pin.

Connect the LED jumper wire to Uno digital pin 2.

Connect the Uno to your computer via USB to power it.

Upload Code

Enter this code into the Arduino IDE:

LED attached to digital pin 2

init() { pinMode(ledPin, OUTPUT); // Set pin as output

void loop() { digitalWrite(ledPin, HIGH); delay(1000); // LED ON

Send the code to your Uno by clicking Upload. A correctly connected LED should flicker on and off once every second! Change the delay values to blink faster or slower.

Congratulations on building and programming your first simple circuit! Add sensors, motors, and displays to experiment. Endless possibilities. Have fun experimenting!

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