Transistor types for the circuit from the previous post can be as follows:
Power transistor: TIP31, BD131, BD241 .. any transistor with Ic>2A and Vce>30V eill do ..
Currnet sense transistor: any general purpose NPN - 2N2222, N100, BC107, BC ..
Other option is to use voltage regulator (as current limitter) + voltage regulator (as voltage regulator); see picture below ..
Basically, idea is the same as with transistors, but realization is based on typical voltage regulators ..
In the example from the picture the output current is limited to 150mA ..
This current can be changed by varying the 8.2Ω resistor: Ilimit ≈ 1.25V/R ..
Regards,
IanP