The humble LM317 adjustable voltage regulator is everywhere ... including driving LEDs and laser diodes. While this circuit may not be as efficient as an LED driver module or a switching solution ...

The LM317 regulator melds with HC4053 CMOS switch to make a 16-W PWM power DAC, charting a less traveled by path to power.

So what’s so exciting about this single-voltage ... circuit is dead simple: a transformer, a full-wave rectifier, an LD1085 adjustable regulator — a low-dropout version of the venerable LM317 ...