I built this on a breadboard. I strongly recommend no one else does. EMF voltage spikes from the blocking oscillator on the left that don't destroy the Transistor or the batteries get stepped up to between 100 to 900V DC. Ten stage Cockcroft-Walton cascade then increases this to God knows what.
I managed to throw a spark 6mm from the output (blue) as well as some decent plasma corona, before I started seeing arcs between the diodes, smoke, and gave myself a few decent shocks. Don't build this. Caps bigger than a few pf will hold enough energy to kill you instantly, even with the source disconnected. After 3 stages the volts will be high enough to start jumping across veroboard tracks, and above 8 stages it'll leap breadboard holes easily.
The simulation is fun to run though, and also tests how much CPU load your phone can handle.
