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19 lines
775 B
19 lines
775 B
8 years ago
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Calculations for the UV LEDs
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The goal is to get a cheap simple LED driver.
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Material:
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- A 18 V power supply is used.
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- LEDs with 3.3 V forward voltage and a max. forward current of 30 mA are used.
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18 V / 3.3 V = 5.4545
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So 4 LEDs can be put in a row. That means roughly 4.8 V have to be wiped out. Taking a 200 Ohm resistor results in 24 mA.
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P = U * I
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So the resistors have to be able to take 115 mW. This is fine with every standard resistor. The risk with this technique is, that the foward current differs a lot, which results in another current going through the LEDs. So a better driver should be developed at some point.
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48 LEDs can be taken, which will result in ~1.2 A. As the power supply can deliver 2 A this is fine.
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