Hi
If we do the maths.
PN2222 .. DC Gain == beta of 100 minimum.
beta = Ic/Ib
Ib = Ic/beta
Ic = LED current at collector = 1000mA
Ib = 1000mA/100 = 10mA base current.
3.3V from the arduino, 0.7 base-emitter volt drop.
voltage across base resistor = 3.3 - 0.7 = 2.6V
V = I x R
Voltage across base resistor = base current x base resistor
base resistor = Voltage across base resistor / base current = 2.6V / 0.01A = 260R
So 270R or 220R would be more suitable to get the transistor to saturate and pass full collector current.
Tom... 