Investigating potential power current sources capable of handling both AC and DC currents using the LM317 current source.

Honestly, nothing — until you start looking at its thermally compensated current limiting circuit. This one is ... low-dropout version of the venerable LM317 — and associated filter caps ...

To demonstrate the simplicity of such a component, [Eric] constructs a current limiting circuit using a JFET and feedback potentiometer then confirms the functionality on a curve tracer.