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Need help with a circuit. Answered

I want to make a circuit that lights up 14 LEDs in parallel. The LEDs require 3.2 volts and 20mA each. If I use a wall wart that supplies 9v dc and 350mA, What resistors will I need and how should I connect them? Also can the current blow my circuit?

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user

sweet! Now is it possible to have too high of a current? and can it "blow" the circuit?

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user

An led is essentially a short circuit. If you put .001 volts over the voltage drop of the led, it will spike the current far above what the led can tolerate, it will overheat and quickly die. Enter the resistor. It converts the series circuit from a short circuit to a 'fixed resistance' circuit which will tolerate the extra voltage without destroying the leds.

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user
stands2reason (author)2010-11-29

You can just put series' of three in parallel. That way you would be dropping 3V across each one without needing a resistor. Not to mention the open circuit voltage on wall adapters is a good bit above what is stated on the supply.

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lemonie (author)2010-11-29


OK straightforward. Re-' says that at 9V you'd need 7 pairs, because 3x is over 9V. Can you get a higher-V supply?

L

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