I plan to show you, with an interesting concept.When I was make pre-amplifier circuit is small. I did not plan on the power supply. It requires low supply current is only 100mA. But the need for dual voltage. Or 3 line is +12 V,-12V and Ground. At that time, I have not the least knowledge and a few equipments. The regulator ICs I use IC7812 and IC7912 (hard to bought). I make this circuit. It works great.
In circuit I use diodes D1, D2, only both because I’d forgotten to add, and this is a low current, using a half-wave diode rectifier enough. and The transformer is 300mA -15V CT 15V that cheap than other sizes.
-IC1-IC2 do not need to hold the heat sinks because the very low currents.
-LED1 is indicator to Power ON that R1 is the current limiter of LED1.
-C1,C2,C3,C4 are first filter that time I has them many so place various 2200uF.
How to built.
This project I put them in peforated board, it easy to use, and so cheap. But at time I put wrong pin capacitor, when entering the power supply, causing it to burst. I was shocked very much.But I do not Discontinued this project.
All my experience, when I was young. About building electronic circuits.
Thank you for reading the poor English story.