Quote:
Originally Posted by ratdude747
i was trying to avoid resistors... i figured that the correct number of LED's in series would be the best solution.
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Do not try to avoid using a resistor. LEDs are not linear devices, meaning that when they get a little warm, their current consumption increases. More current leads to more heat leading to more current - this is known as thermal runaway. It ends in smoke.
Go ahead and use your four LEDs in series, but then add a small-value resistor - say, 20 Ohms or so (do the math) - in series. This will prevent thermal runaway.
The voltage drop across an LED is determined by its chemistry (and therefore the color it produces). Blue & White run at about 3.5 volts, red runs at about 1.8 volts. This is a physical quantity, not generally subject to change. Keep this in mind.
My advice is to use a milliammeter to measure the circuit current, and adjust your circuit to reach the necessary current, ignoring voltage.
Oh, and if you want, you can use ONE spike to power 2 colors. Hint: what's the "D" in LED stand for??
