Circuit Project Electronic

SG3525 DC/DC Converter 12V to +35V,-35V Switchmode Power Supply For Car Audio
The selected switching topology is called a “push-pull” converter, because the transformer has a double primary (or a “centre-tapped” one, if your prefer). The centre tap is permanently connected to the car battery (via an LC filter to avoid creating peaks in [...]

Click to View circuit and Read more 
A solar cell radio used a 3V (or two 1.2V) Ni-Cad battery in it. The battery can not be removed.  …

Source : http://www.geocities.com/dsaproject/electronics/cook-book/cook-book.html

Click here to view Circuit and PCB
Power supply regulator 0-35V 2A by IC LM723 + Transistor 2N3055 & BD140 & A671
The Circuit power supply regulator 0-35V 2A by IC LM723 +
Transistor 2N3055 & BD140 & A671 , It nice Power supply, For all electronic user.

Note:
To use transformer 3A, The VR1 - 1K perform fine [...]