Krill Labs - Beer Bottle Capacitor Bank

About:

So I've already built a high voltage generator capable of producing 25,000 volts of electricity. That thing can make arcs, sparks, corona, and drive a Jacob's Ladder, now what else could I do with it? Store it! Not to mention, this is the next step towards a working Tesla coil. Normal high voltage capacitors tend to be very expensive, but with a little extra time and ingenuity, this dirt cheep alternative can prove to be almost just as good. Each beer bottle has a voltage rating of over 75kV, a capacitance of 3nF and is considered one cell when used in a salt water tank capacitor. My tank capacitor is comprised of 6 cells for a combined capacitance of 18nF.

Charging the Capacitor:

       I can not directly connect my capactiors to the HV supply. The capacitors would not even charging. This is because I am using a flyback/ignition coil for the HV source instead of a neon sign transformer (NST). And to make those kinds of transformers work I'm operating it at well over 60 Hz with a 555 timer. In the range of 5 to 15 kHz. So think about the output of the ignition coil, sure it's high voltage, but its also high frequency AC. What is AC? Back and forth, right? I'd be charging and draining the capacitor like a thousand times before it ever has a chance to fire across the spark gap.
       Solution? Rectify the ignition coil's output with diodes (if used in a Tesla Coil, this would make it a DC Tesla Coil), OR I could use a HV supply with a much lower frequency, like an NST. An NST will still output AC, BUT the frequency is low enough that the caps will at least have a chance to charge up and fire across the spark gap before the voltage swings the other way.
       Below are some different diode configurations I tried for rectifying my HV current.

I wanted to see what would happen if I used just one diode. You can see that when the AC is traveling the wrong way,
the diode does it's job stopping it, but the voltage is so high that the current doesn't care! It jumps right around the diode!

Here I have a string of eight 1000 volt diodes for an 8000 volt half-wave rectifier.

My final version is 16 8kV diodes in a bridge arrangement for a 32kV full-wave rectifer.

Sparks:
These are soooo neat! While the arcs are not as colorful or as flashy as the HV generator's, these are quick, extremly bright, and
indescribably loud. The frequency of the pops can be controlled by adjusting the distance of your spark gap. The farther apart, the
higher the voltage but the lower your frequency. This is because it takes a higher voltage to jump the greater distance, and it's
a lower frequency because it takes longer for the caps to charge up. Put the gap closer together and the lower your voltage but
the higher your frequency.

Mechanical Spark Gap

As I kept adding capacitors, it was getting more and more dangerous for me to manually move the spark gap, so I came up with this, a mechanical one that I can adjust remotely.

Capacitor Housing

Having the beer bottles just sitting on my table connected with rods and stand-offs was fine for initial testing and prototyping but it's by no means practical. It's impossible to move as a single bank, it's easy to accidently knock over because of the insulation stand-offs, and its dangerous because of all the exposed parts. My solution to all this was to build a universal housing.

The bottom inside is aluminum foil to commonly ground any caps onboard. Also, the side rails are not just walls for holding the bottle caps up right they also double as handles for convinient transport.

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