This little power supply uses an ordinary 120VAC to 9VAC step-down transformer to deliver 1500Vrms. You will need two power resistors, both 50ohm 10W. These can be bought at Radio Shack. The transformer is wired backwards. 9V windings connect to 120V. The primary should develop around 1500Vrms across the primary (secondary in this case). If you need more voltage/current you can go with smaller value resistors, but don't get carried away or you'll smoke your transformer. This power supply is suitable for powering a small laser. It is not recommended that you draw arcs with this without some form of current limiting. Here is a simple schematic showing a simple 1500VDC laser supply with half-wave rectification.

120VAC <----/\/\/\------)||(------------|<----<|----<|---------->HV OUT (-)
                        50          )||(              4007     4007  4007
                                      )||(
120VAC <----/\/\/\------)||(---------------------/\/\/\----------->HV OUT (+)
                         50                       Current limiter (470k typ.)

Remember that the 9V winding connects to 120VAC and the 120V winding is your high voltage output. If the transformer is shorted it may be destroyed. This is because the reactance of the 9V winding drops as a load is applied to it's output. The drop in reactance causes more power drain which the 9V winding can't handle. Output in current is 4.5mA using the 470k current limiting resistor. A capacitive filter will cause the output of this circuit to be around 2100V.

Back