23 lines
316 B
Markdown
23 lines
316 B
Markdown
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# Calculations
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## LED Formula
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### LED Spec:
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2.8v (forward voltage)
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20ma (current)
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Vsupply = 5v (Pi Power)
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Vf = 2.8v (Led Volts)
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R = resistor value
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If = desired current
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Vr = Vsupply - Vf
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R = Vr / If
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Vr = 5V - 2.8V = 2.2V
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R = 2.2V / 20mA = 110 ohms
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Make sure to add some play room, we use a 120 omhs resistor
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