18/12/2024 5:15 am
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I’m using an LED with an Arduino. While researching, I noticed that many people use different resistor values, such as 100Ω 220Ω, 1kΩ, or even other values. This got me wondering: how do you decide which resistor value to use with an LED, and how do you calculate it?
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06/01/2025 6:47 am
The resistor value for an LED is crucial as it limits the current flowing through the LED, protecting it from damage. Choosing the right resistor value depends on the LED's specifications and the voltage of your circuit. Here's how you can calculate it:
Formula-
R = (Vsource - Vf) / ILed
- Vsource is the Arduino’s pin voltage (e.g., 5V or 3.3V).
- Vf is the LED’s forward voltage (e.g., ~2V for red, ~3V for blue/white).
- Iled is the desired current (usually 10-20mA for standard LEDs).
For example, with a 5V source, a red LED (Vf = 2V), and 15mA current:
R = (5V - 2V) / 0.015A = 200Ω
People choose different resistor values based on:
- Brightness: Lower resistors (e.g., 100Ω) make LEDs brighter; higher resistors (e.g., 1kΩ) dim them.
- Power source: Different sources (3.3V vs. 5V) need different resistors.
- LED specs: Forward voltage and current ratings vary by LED.
