fungus:
The max current through NP2222 is 650mA.The max current I can flow with a 5V signal at the base
This statement is wrong on many levels.
The NP2222 works when current (ie. amps) goes through the base, not when a voltage is applied to it.
The transistor has a gain of 100 (or more) so you need to allow 6.5mA (or more) of current through the base. Normally you use a 330 Ohm resistor between the Arduino pin and transistor base for this sort of transistor. This allows enough current to fully turn on the transistor.
OK, so the transistor is (I see, its like a diode in that respect) a current device, and 6.5mA will completely close this one; thanks.
So, how much current or power can be controlled with this? I am illuminating several LED's and need to know if I'm pushing the limits of the transistor, or I'm OK. Any help there?
thanks, and I did mention I'm not an electronics guy, but I am a quick study XD