I thought that it would be much more appropriate if the current limiting circuit was made to be polarity independent, so it would work with AC as well as DC of unknown polarity. I took the easy route: I connected the current limiting circuit up to the + and – leads of a bridge rectifier. I realized that it would add a volt and a half or so to the minimum supply voltage.
The limiting circuit (Fig.1 here) was the classic one: a transistor for passing the current, with a low value resistor in series with the emitter, to ground. The voltage across this resistor is used to turn on another transistor, which then shunted away the base bias current of the pass transistor. This bias current was from a 22k resistor to the collector of the pass transistor. The only difference between my circuit and the one in Fig.1 is that mine has a 470 ohm resistor in series with the base of Q2. The whole thing fit on a small circuit board, with two white wires since the polarity was not important.
Back to experimenting…