Coin Shrinker

Pulsed power can do amazing things, one such feat is shrinking money.  The idea is to take a large capacitor (storing many thousands of joules at a few kV at least) and discharge it through a small work coil.  In the center of the work coil is the coin to be shrunk.  Now, somewhere around 75-100kA (yes, kilo-amps) flows through the work coil, containing 10 turns for my machine.  This induces a current theoretically of 750-1000kA in the coin (really less because of resistance and the coupling between coin and coil is not unity K=1).  But in any case, the currents are enormous.  Since they are flowing in the opposite direction, the conductors repel with great force, so much force that the coin is shrunk and the work coil explodes violently into hundreds of little pieces.

So recently I managed to get ahold of a Maxwell pulse capacitor, rated 70uF at 12kV (5000J).  Its rated for 100kA per shot with 20% voltage reversal.  Its fault rating is 200kA with 80% voltage reversal (it can't take nearly as many of those shots of course).  I don't know its previous use (or abuse), but Bert Hickman has been using a pair of these same capacitors for his quarter shrinking business with a few thousand shots on them with no problems at all.

I must warn the reader that 1) a capacitor like this is absolutely lethal, no second chances if you happen to contact this capacitor, you would be lucky just to lose an arm or leg.  2) The shrapnel produced by the work coil is also potentially lethal, it's moving at an extreme velocity and will easily penetrate skin and bone.  Just take a look at what it did to the 2" steel pipe I attempted to use as coil containment.  3) When fired, an extremely loud shockwave is produced from the coin/coil as well as the HV switch.  I have all of these things enclosed in a 3/4" plywood box for extra sound-deadening, but hearing protection is still a MUST!!  If you are new to high voltage or high energy experiments, then I do not recommend playing with capacitors of this size, your first mistake can easily be your last. 

Pictures of my rig: