Here, you can see me first DIY tesla coil that I've made. Moreover, I saw that 12v from the original power supply are not the best choice for this coil, so i connected a 24v 5A power supply block, and a tiny fan(so it cools down the whole environment)
Have you ever wondered what hides inside these mysterious "Plasma Spheres"? Well.. Recently I had the same question, So, I disassembled it. First of all, turns out that the sphere itself is completely sealed(like an ampule) and the main electrode is just a small wire with a high voltage. Take a look on the pictures, you can see that the voltage is high enough to power up a lamp! Thats so cool!