250 kV High Voltage DC Power Supply with Neat Trick for Switching Polarity

  
Inside:
Repository
The Cockroft-Walton multiplier uses a cascaded series of diodes and capacitors to generate a high voltageDC potential from anAC input through acircuit topology thatuses diodes to charge capacitors in parallel and discharge them in series. The output polarity of the Cockroft-Walton multiplier depends on the way in which its diodes are oriented, so
250 kV High Voltage DC Power Supply with Neat Trick for Switching Polarity - schematic

the output polarity(referenced to ground)of a high-voltage DC power supply is usually set during the design. However, since some of our physicsexperiments requireone or the other polarity, we build our Cockroft-Walton multipliers with an extra capacitor so that we can make our HV power supplies output either positive or negative high voltage referenced to ground. The schematic for our reversible  Cockroft-Walton is shown in the following picture (click to enlarge): If the high-voltage AC output of the flyback is connected to point A  of the voltage multiplier, and point B  is connected to ground, then the output at point D  will be positive. If however point C  receives the high-voltage AC, and point D  is connected to ground, then point B  will be negative. Banana connectors are theninstalled onthe plastic container and wired directly to points A, B, C, and D. The connectors must be sealed very well using silicone RTV: The plastic container should then be filled with pure mineral oil (may be purchased at a pharmacy) to completely submerge the multiplier circuit assembly, which prevents high voltage breakdown between components: In this AC power supply, a push-pull oscillator drives a TV flyback transformer from an old color TV (a flyback without embedded tripler). The well-known hack is that the original primary of the flyback is not used. Instead, new primaries are made by winding two sets of four turns each of...



Leave Comment

characters left:

New Circuits

.