Instructables

Step 9: Generating an extra-high tension

Picture of Generating an extra-high tension
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There are many methods of generating high voltages, including but not limited to Tesla coils, induction coils, Marx generators, Van-De-Graff generators and Cockroft-Walton cascades. Even some unorthodox methods such as piezoelectric and pyroelectric crystals exist.

While all of these methods have their advantages and pitfalls the Cockroft-Walton voltage multiplier would be the circuit of choice for this project. Properly designed cascades are capable of transforming large powers with comparatively little loss, and their lightweight and small stature make them well suited for a small x-ray generator. 


Refer to the first schematic. By feeding an alternating current into this circuit, one can sacrifice cycles and current in return for a doubled, tripled or even quadrupled DC voltage. All and all the circuit's mode of operation is rather simple, as it is nothing more than a cascade of Greinacher voltage doublers [second image]

On the negative alternation, the bottommost plate of C1 is charged to -10kV via D1. Afterward, the positive alternation puts C1 in series with another 10kV creating a total potential difference of 20kV, which is shared with C2 via D2. This 20kV can then be discharged, or another cascade may be added to create 30kV, or another to make 40 kilovolts. In reality though, it takes several more cycles for the stack to reach its full potential due to parasitic resistances limiting what would otherwise be very high currents.
 
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