The NPN transistor in saturation has a V CE(sat) voltage drop of about 0.20V-0.25V which, when added to the 1.25V drop of the internal regulator, will yield a total voltage drop of 1.45V-1.50V. Using ...

IC1 LM317LZ 200mA, TO-92 ($0.59) – This is the smallest common LM317 voltage regulator. The part linked can supply 200mA, but 100mA is more common.

Take advantage of current control topologies without self-heating error while retaining the 317/337's fault protection ...

The results are shown, in comparison to a typical LM317 voltage regulator, in Fig. 2. Both regulators are measured in the same test setup, ...