Enter the voltage source, the voltage drop across the LED, and the current through the LED into the calculator. The calculator will display the needed resistance for the simple circuit.
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LED Resistor Formula
The following formula is used to calculate the resistance of an LED circuit.
R = (Vs – Vl)/ IL
- Where R is the resistance
- V is the voltage of the source
- Vl is the voltage drop across the LED
- IL is the current through the LED
LED Resistor Definition
An LED resistor is defined as the total resistance in an LED circuit.
LED Resistor Example
How to calculate LED resistor
- First, determine the source voltage
Measure or calculate the voltage coming from the source.
- Next, measure the voltage drop across the LED
This can be done by measure directly after the LED and subtracting that value from the source voltage.
- Next, measure the current across the LED
Measure or calculate the current across the LED.
- Finally, calculate the resistance
Using the information from steps 1,2 and 3, calculate the LED resistance.
The LED resistor is the total resistance needed for a simple LED circuit in order for it to work properly.