Sure, you can use the PSU. The 3.3 volt SHOULD be OK, but it's a good idea to check the voltages each time you add or change any thing.
That power supply would be CV ( constant voltage ) so the amps that are consumed will depend on what is attached to it.
Over simplifying for ease of understanding:
A resistor in series with an LED is known as a 'current limiting resistor'.
You can attach up to 6 LEDs to that supply in parallel. You can accurately adjust the amps used by each LED by putting a 1 watt resistor in series with each LED The ohms value of the resistor will have to be determined by either experimenting unless you have a variable PS that you can use to determine the exact volts needed for each LED. The idea is that the resistor will consume a small portion of the voltage and the balance of the voltage will be used by the LED. Test the assembly by putting an ammeter in series with each led and checking the amps.
IN THEORY: the 3.3 volt supply should be safe for the LEDs without a resistor in almost all cases. Unfortunately there CAN be some LEDs of that type that will draw much more current at 3.3 than it should. There might also be some that under perform at that voltage.
caution; do not run the LED at full power without mounting it to a heatsink. They do get damaged from the heat fairly quick. They also burn your fingers, Ask me how I know.
Last edited by danlb; 05-13-2012 at 05:24 PM.
Measure twice. Cut once. Weld. Repeat.
( Welding solves many problems.)