Regulating voltage for LEDS and LED WIZ?

[RobbyMac]

Forgive my ignorance, as I have not tinkered with LED Wiz yet (Or any other led boards if there are any)

Rather than solder a gazillion resistors, couldnt a voltage regulator be used instead?
Does LED wiz allow you to control voltage?
or is a separate power supply required? I saw this on their site: "32 uniquely controllable outputs and up to about 500 Hi-Output LEDs per board (15+ per output, external power source required for this type of operation)" but it confused me slightly, and I'm unsure if the power supply is provided unless you exceed a certain amount of leds.

If a separate power supply is required or possible, then couldnt a voltage regulator be used (prior to it reaching LED Wiz), to avoid using resistors?

[BobA]

Different colored LEDs require different voltages.  In addition variations in individual LEDs cause slight differences in voltage drops as well so current limiting resistors are the standard way of interfacing unless the LEDs are already set up (internal resistor) for 5v or 12 v in which case a regulated supply can be used without dropping resistors.

[MonMotha]

You CAN run LEDs off a suitably chosen regulated voltage without a resistor, but you have to be careful since rather small changes in voltage can destroy the LEDs, and choosing the voltage can be tough since the datasheet numbers are "typical" and do vary.  If you have a grab bag of LEDs, you won't be able to get them all at the same brightness, either.  If you don't care about any of that, then yeah, have at.

The reason for the resistor is to attempt to overcome the nature of LEDs that very small fluctuations in voltage can result in a large change in current and therefore power which could destroy the LED.  LEDs aren't nearly as forgiving of voltage issues as, say, incandescent light bulbs.  In fact, they can be so intolerant of it that it can be impossible to get LEDs of the same lot to light at equal brightness with a constant voltage source.  The resistor swamps this intolerance (it's an exponential dependency of current on voltage) with the "well behaved" nature of the resistor (which is a linear dependency of current on voltage).  If you have different color LEDs, then, at minimum, each color will need a slightly different voltage.

If you have a bunch of LEDs and don't want individual control, you can wire them in series using a single resistor.  This is how long strings of LEDs for lighting purposes are often made.  Choosing the resistor isn't a terribly complicated process.  Just add up the expected voltages on the LEDs, choose the lowest current that they can all handle (this does NOT add as the current runs serially through each LED), and choose R = (Vs-Vl)/I where Vs is your supply voltage, Vl is the added up LED voltages, and I is the expected current in amps to yield a resistance value in ohms (remember that 1mA = 0.001A).  Vs-Vl must of course be positive and should be at least 1.5, so you may need to use a 12V or 15V supply instead of a 5V.  Note that the power in this resistor can become somewhat substantial if you use an inordinately high voltage.  P=I^2*R (same definitions for the variables as before).  You can buy a 1/2W or even 1W resistor if you need to.  The LED-Wiz is probably good to a 25-30V supply, but check the manual before using anything over 12.

Of course, you can have several strings each with its own resistor.  This is one way you get 500 LEDs on 32 outputs from the LED-Wiz, in fact.  You'd only need 32 resistors, then.

[RobbyMac]

OK.
I have all bright white led's, and in theory should all require the same voltage. At most I will have 2 in series for any given output/button. I will want individual control. And after reading the helpful posts it appears I will be using resistors rather than any sort of voltage regulator.
I assumed there had to be a reason why others weren't using regulators, and now I know why.