The humble LM317 adjustable voltage regulator ... describes how the LM317 can be used to regulate current rather than voltage to provide a constant current source under varying load.

Making a precision programmable current sink by floating the long-forgotten anode pin of the TL431 voltage regulator.

The current source uses a 24-volt switch-mode power supply and the popular LM317 adjustable voltage regulator. The ‘317 can be configured in a constant current mode by connecting the chip’s ...