Project list

High voltage capacitor

Init

Time:

20.12.2005 5:44:59PM

Description:

For Tesla coil "on the old way" high voltage capacitor is also needed. That capacitor must be able to hold very high voltages, and have as less losses as possesible.
Usually people are using a bunch of capacitors connected in series and parallel (MMC, Multi-Mini-Capacitor), but as I was on vacation without any hardware sotores nearby, and no TVs in junk, I had to manage with things I have.
First, I tryed with Lyden jars, but later I figured out that Layden jars have too much loses, and my flyback can't fill them, even with a voltage tripler, for sparks longer than 1mm. That bottles has to be filled fast - I managed to do that with a long spark gap inserted in series with tripler's output. One bottle has around 850-950pF.
Than I tryed to make capacitor made of 2 paper, and 2 aluminium layers. That condensers can't hold more than 1000V, because above that voltage, paper starts to conduct. Maybe I could make a big MMC with that type of condensers, but that's too much of work. One condenser made from only 1 paper from one mini-block gave me 4nF.
As I figured out that plastic is very good isolator, I made condenser from plastic cups. That capacitors appeared to be very good, and it's very easy to expand it with another aluminiumificated cup. The good idea would be to connect lowest part to ground, so that parasite capacity can't appear...
One cup with aluminium inside and out has capacity of around 500pf, until 2 cups aluminiumificated only from the outside has around 350pF.

Videos:

Small and loud sparks. Someone could think that there is burgalar in my garage! :) That was first experiment with cup capacitor. Video isn't very realistic... There is something strange - sparks aren't there where they should be, and they last too short.

Example of a bit stronger spark.(Also a bit unreal)

Pictures:

Layden jars, also called saltwater capacitors

Rolad-condenser (don't know real name)

Condenser breaked out...

I disassembled that condenser to see what went wrong...It looks that I melted that plastic cup on one place while gluing it with a melted plastic - it didnt break between aluminium layers, but a bit above it.

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