Where did get the 150 mA?It looks like wants about 150 ma in the leds. If so his Darlington with the led in the emitter should be ok.
I think the TS just forgot to modify the value of resistor.18 volts, 1 led and 100 ohms.
by Robert Keim
by Aaron Carman
by Duane Benson
by Aaron Carman