styropyro

hot vacuum tube tesla coil

Added 2022-12-15 01:21:43 +0000 UTC

I decided to break out the vacuum tubes again and build a classic vacuum tube tesla coil circuit. I seem to have gotten lucky picking circuit values because this thing is running HOT. The screwdriver I'm using as an output electrode is melting quickly at 9kW into the circuit.

My favorite thing about the classic VTTC circuit is its ability to make a hot arc to a grounded electrode, and this coil is a prime example of that. The circuit features a half wave voltage doubler which means the coil only operates on half of the AC cycle, and interestingly, this is crucial to how it operates. If you run it on the full cycle with smoothed DC, the arc shrinks dramatically, even though the power input is increased. The voltage ramp from the doubler helps the arc grow to much longer lengths than if the drive voltage is kept constant.

In my circuit I take that a step further by using a SCR to cut the ground connection on the tube every other cycle, which means the coil ends up running at 30Hz rather than 60Hz. This makes an angrier and longer arc.

Next step is to either move this beast outside so I can run it on my 200A breaker, or run some thick cable from my breaker to my cage so I can run it harder there. The tube is only rated for 8kW, but I'm pretty confident I can push 20kW through it for short runs. It should look pretty incredible and it'll be one of the most powerful VTTCs ever built.

PS: note the ground strap on the tesla coil arcing to the floor in the background. it's being powered wirelessly by the vacuum tube circuit :p

PSS: patreon thinks this post is porn for some reason ??? (i guess that means the tesla coil is REALLY hot)