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How to Wire Resistor Load in LED Lights | Sciencing
LED's emit a single wavelength color of light, with a brightness proportional to the current supplied. Various styles of LEDs have different operating specifications. LEDs can be ran off multiple voltages, but a series resistor is required to limit the current in the circuit. Too much current in an LED will destroy the device. As with all diodes, LED's will only allow current to flow in the direction from the anode to the cathode. Examine the specification sheet for the LEDs which you wish to use in your circuit.
Resistors to pos or neg side of led? two answers??
If you read about LEDs, you will notice that everyone tells you, that you need a current limiting resistor. But mostly they do not tell you why. If you look at a datasheet of an LED, you will notice that graphs shown are not linear.
Maybe you know the answer, or maybe everyone already assumes that you should know how to get to the answer. What power supply? Part of a larger circuit? Playing with LEDs is supposed to be fun, and figuring out the answers to these questions is actually part of the fun. But how do you know what numbers to plug into that formula to get out the right resistor value?