** DISCLAIMER - Unless you know what you are doing, dont try this. This blog post does not contain enough information to try this safely. **
One thing on my project pile is to construct a HV supply, suitable for use in Kirlian photography and similar experiments. An extremely simple circuit can be used to generate reasonably high voltages from an old flyback transformer.
Some first experiments generated pretty arcs, and showed that it might work. I made a bit more progress now. The supply is now contained in a box, to keep stray fingers out, and it contains a rectifier, so it can be fed AC power. Thus, it can be powered from a variac. This is a nice source of adjustable power, and it will prevent me from blowing the lab supply with this thing - its a really ill-behaved load for any supply.
Heres a pic of the setup. The HV supply on the left, variac on the right. Yep, definitely time to put the variac in a case.
At this point, raising the voltage much more leads to unwanted arcing, such as this one from the HV wire to the case.
A bit more fiddling, and it will be time to try some Kirlian stuff.