The circuit above is a DC to DC converter using a standard 12 VAC center tapped power transformer wired as a blocking oscillator. The circuit is not very efficient but will produce a high voltage usable for low power applications. The input battery voltage is raised by a factor of 10 across the transformer and further raised by a voltage tripler consisting of three capacitors and diodes connected to the high voltage side of the transformer. The circuit draws about 40 milliamps and should operate for about 200 hours on a couple of 'D' alkaline batteries. Higher voltages can be obtained by reducing the 4.7K bias resistor. More information on blocking oscillators can be found here: Blocking Oscillators

Copyright 2006 Bill Bowden

1x 12.6 VAC / 450mA Power transformer (Radio Shack 273-1365)
Misc condensators, resistors, etc.