That will help.
R2 depends of load, something about 3-5 Ohms.
Zener's voltage is 6.5 V, R1 - 5...10 kOhms
Transistor - almost any NPN BJT allowing current 1 and more Ampers and voltage 30 and more Volts, heatsink is requered.
All parts can be extracted from almost everything.