Electronics & Circuits
Intermediate

LED Series Resistor

Resistor to safely drive an LED.

Formula

R=Vs−VfIR = \frac{V_s - V_f}{I}

Variables

V_sSupply
V_fForward voltage
ICurrent

Example

(5-2)/0.02 = 150 Ω

Did You Know?

Choosing the right series resistor keeps an LED bright without letting excess current destroy it.

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