electronics · 44 seconds
A tiny resistor does an essential job.
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Estimate a resistor for a 3.3 V supply, 2 V LED and 5 mA target.
Illustrations generated with OpenArt. Narration uses free local Kokoro neural voices. Illustrations are visual aids; the written lesson carries the explanation.
Use a 5-volt supply, a red LED with a modelled 2-volt forward drop, and a target current of 10 milliamperes.
5 V supply · 2 V LED
The resistor must drop about 3 volts. Divide by 0.01 amperes to get 300 ohms.
(5 − 2) / 0.01 = 300 Ω
A standard 330-ohm resistor gives roughly 9 milliamperes in this simple model. Its power is about 0.027 watts.
330 Ω → about 9 mA
Forward voltage varies with current and temperature. Check polarity, current rating and resistor power before building.
An LED is not an ohmic resistor
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