LOCAL ENGINEERING ESTIMATE

Low-voltage LED resistor

Estimate a series resistor at one DC operating point.

FORMULA & LIMITS

Understand the model

R = (Vs − n × Vf) / I; Pr = I²R

For isolated low-voltage learning circuits only, not mains wiring. Vf, supply tolerance and temperature change current; select a rated part with suitable margin.

Changing an input invalidates the previous result. Check units before calculating again.

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