This is 5v 12v dual power supply circuit using 2N3055 and Zener diode for 12V then to LM309 or IC-7805 dc regulator IC for 5V output which easy circuit [...]
CAR Radio transmitters to use in home, need a ham radio power supply DC-12V or high current 13.8V power supply with enough power out of 5A - 30A. [...]
Small Zener diode voltage regulator circuit with PCB, using transistor and few parts. it is simple and cheap fixed dc source circuit. As one of best choice.
First choice of Fixed Regulator using family IC-78xx. It is easy to use, cheap, popular for a long time.
Build 12V high current power supply, do not need PCB. We use a hammer and nail ! Why?
See two negative Voltage Regulator circuit ideas. Do you know? we can use PNP transistor and Zener diodes in these example circuit 12V,9V at 700mA output