This is one of my high voltage Power Supply Units (PSU). It's a 25 kVA 14.4 kV to 120/240 volt distribution transformer, or pig. Normally it's used to step down distribution voltage from 14.4 kV to 120/240 volts for residential use. However, I hook it up backwards to get 14.4 kV out at 240 volt input. (I've also been known to feed it 280 volts, to get 16.8 kV out). Pigs require external current limiting.

This is my 225 amp welder. I use it to current limit the pig by shorting the secondary leads and connecting the primary in series with the pig. By changing the welder setting, I can adjust the current fed to my pig. This is known as inductive ballasting.

This is my 15 kV 120 ma Neon Sign Transformer (NST). An NST is a current limited high voltage transformer. Most NST's consist of two secondary windings connected in series, with the common tap grounded.

This was my first Franceformer 15 kV 30 ma NST. This NST has been blown up and rebuilt three times. During the first rebuild, I removed two sets of the current limiting shunts, allowing me to get a little more current out of it, at the expense of reliability. Tesla coiling is fairly hard on NST's. That's why I mounted a safety gap on top. The safety gap gives the two high voltage outputs a place to jump to ground, if the voltage rises too high. The gaps are adjustable, and are currently set for just over 15 kV.

These are my two France NST's, depotted with half the shunts removed.

This is their new home, ready to be wired and filled with oil. It actually has enough room for three nst's.