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Coding tips and build notes by Mahir Faysal, a student web developer in Bangladesh: tested Python, HTML, CSS, JavaScript and PHP tutorials, plus notes from my Next.js and Gemini projects. Sample posts are marked and drafts stay in the admin area.
To calculate the resistor for an LED, subtract the LED's forward voltage from the supply voltage and divide by the current you want: R = (Vs − Vf) ÷ I. For a red LED (about 2 V) on a 5 V supply at 20 mA, that's (5 − 2) ÷ 0.02 = 150 Ω.
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