If you are looking for DC Voltage Reulator be simple. That can give Current tall about 3A and fine voltage get from 0-30V. As a result please consider this circuit before, it is easy. Because of have no the integrated circuit. Use the transistor [...]

A Jacob’s Ladder is very easy to make. All you really need is a high voltage power supply, two metal rods, and some kind of insulating support for the rods. The power supply only needs to be of a sufficient voltage to break down the air at the base of the V (5kV and up [...]

This is circuit high voltage Power Supply DC Adjustable Voltage 0-300V 0.1A max. It is a simple circuit which can provide an Variable voltage source of 0 to 311V by R3-500K
The supply is short ciruit proof and the current is limited to about 100mA.
Source: http://www.geocities.com/tjacodesign/300vsup/300vsup.html