The humble LM317 adjustable voltage regulator is everywhere ... [Afroman] describes how the LM317 can be used to regulate current rather than voltage to provide a constant current source under ...
an LD1085 adjustable regulator — a low-dropout version of the venerable LM317 — and associated filter caps and trimmer pot to adjust the output between 2.2 and 5.5 volts. The current limiting ...