Help! Almost killed by exploding capacitor! What did I do?

[sparks]

   Tesla did exactly what you did.  He built up 40,000 volts using the entire capacitance of the distribution system supplying his resonator.  Then he shorted this capacitor into another capacitor.  This second capacitor he shorted into a special inductor which appears again as a dead short to the second capacitor but is really a magnetic capacitor.  This circuit would then oscillate at whatever frequency he designed into it.  The trick is in the shorting device.  The faster you short the primary capacitor the better.  Tesla would use a plasma as the shorting device.  Plasmas are the best conductors around.  Latter on with the creation of the vacuumtube rectfier the plasma was contained without the pesky air problem.

     After a few input cycles there was way more amperage surging in the secondary tank than in the primary.  At this point the only energy input needed was to overcome resistive losses.  Latter on he designed the whole secondary resonator so it happened all in one device and inductively coupled the input to excite the resonator.   No resistive damping of the secondary resonator at all.  Just emwave after emwave energy within his circuit.  Below is his quote about one of his earlier experiments.

Yes; I charged the condenser with 40,000 volts.  When it was charged full, I discharged it suddenly, through a short circuit which gave me a very rapid rate of oscillation.  Let us suppose that I had stored in the condenser 10 watts.  Then, for such a wave there is a flux of energy of (4 x 104)2, and this is multiplied by the frequency of 100,000.  You see, it may go into thousands or millions of horsepower.

    40,000 volts discharged into a .1ohm resistance will give you an amperage of 400,000.  Then ring it 100,000 times.

[TinselKoala]

You can short the caps thru the coil--what you don't want is for the power to be reflected back into the capacitor during the discharge cycle. A cap can discharge into an inductance over time--this discharge will have a characteristic frequency and it will also have a "damping" constant--how many cycles before all power is dissipated. The cycles are AC, so if you have a high frequency and no damping,  when the first cycle comes quickly back into the cap, it has reversed polarity and will likely blow a cheap electrolytic. So the key to discharging caps into coils is to avoid this reflection of power, by choosing lower frequencies and "critical damping" which means that all the power in the very first cycle is dissipated in the coil, and doesn't come back to blow your cap.
So it's a matter of matching inductances and resistances to your caps.

Next problem is switching.

[konduct]

You can short the caps thru the coil--what you don't want is for the power to be reflected back into the capacitor during the discharge cycle. A cap can discharge into an inductance over time--this discharge will have a characteristic frequency and it will also have a "damping" constant--how many cycles before all power is dissipated. The cycles are AC, so if you have a high frequency and no damping,  when the first cycle comes quickly back into the cap, it has reversed polarity and will likely blow a cheap electrolytic. So the key to discharging caps into coils is to avoid this reflection of power, by choosing lower frequencies and "critical damping" which means that all the power in the very first cycle is dissipated in the coil, and doesn't come back to blow your cap.
So it's a matter of matching inductances and resistances to your caps.

Next problem is switching.

Okay. Both of those replies are a great help to me.  I have read a lot of the tpu/resonant coil posts without knowing much about it however I am a musician/engineer and have done a lot of research into frequency, math, ratios, etc...so I understand the principles behind the devices, but not the physical designs.
I have no experience outside of putting batteries in something. I like the fast available discharge of capacitors though.

So you understand what I'm trying to do. I've simply started testing a crude Flynn Parallel Path apparatus. I've built one large, chunky, probably inefficient stator...which requires a fair amount of current to properly "fire". It's a monster...using thick steel and strong magnets and rather thick solid copper wire on the coils,,.not magnet wire.  I haven't made much progress because I have no idea how to control the input current needed.

I can get the volts, but not the amps...I went from no power to a 12V battery jump start cell...which is way too much amperage...probably 300 Amps? What I've got now is an AC>AC transformer that outputs around 12V and 2500 mA running to what I believe is a 15 amp rectifier out of an old RC battery charger. That's roughly enough to test further...BUT...when I short the coil...the transformer buzzes and the current to the coils reverts to AC? How can I fire the coil without blowing something up? I thought about a load to "soak" up the juice after the coil but I think that would take away from the coil power? I know I should educate myself better but it makes more sense coming from fellow experimenters. The stator has a tremendous magnetic output using the parallel path. I believe that the path to actual overunity with it may a simple oscillator type setup or ... imagine Paul Sprain's device with a flynn parallel kicker coil at the end? That's as open source as I can put it...just so ya know! 

Once I'm comfortable with these caps and coils...I'll start digging into the sacred math and music frequencies a la Tesla.... Thanks again guys.

//Fun tidbit of info...one of my family members actually represented Edison as one of his lawyers back in the days of the heated electricity distribution "wars".

[konduct]

You have been very lucky mate!

30 meters is 90 feet, any idea with how much force the little alluminium elco shell can hit you when at close range?
The elco in question was no longer then 6 by 15mm.
I now always doublecheck the polarity of elco's as you understand.
I hope all experimenters read this thread because it can save their lives.

My hand knows how much force for sure...the whole case shot off in one piece...only about .375 inches in diameter. It probably would have broke my nose or poked my eyeball into the back of my head given the opportunity...got some safety glasses in my kit now for sure! Especially since I'm no EE.

[starcruiser]

I would bet the power source was AC and the capacitor was an electrolytic, the P/S output would pop the cap, especially if it was close to a harmonic of the resonant point of the cap.