This is Multi voltage power supply circuit  as electrical circuit to supply DC power positive and negative. It also has multiple power levels as well. The equipment it easy to buy and affordable. Operation of this circuit, when T1 was to convert the AC voltage from 220 volts down to 15 volts, and D1-D4 connected to circuit Direct Contact bridge rectifier . Will act as a rectifier AC DC Then C1, C2, C5 and C6 serve filtered flows smooth and then, through to the leg 1 (Vin) of IC1 and IC2. By IC1 (LM7812) acts Direct loans isolate pressure for …
Today I find a negative power supply units circuit on 9Volt sizes to give my friends. But the most circuit is positive voltage supplies only. Therefore I think will get back to the direction of the electricity to negative form. When use Transistor 2SC1061 or TIP31 as a result give current about 1A and Transformer must have 1Amp size with. Now we change with TIP42 PNP transistor type and switch polarity of Zener diode, Electrolytic capacitors, and more other parts same one. Request have fun 9V Negative power supply units. but you want to builds easily maybe use IC-7909 dc …
Here is circuit Power Regulator +12V,-12V. Use IC –LM7812 for +12V and IC LM7912 for -12V. This is circuit for Preamplifier play nice Music.Detail See in circuit. 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 …