Capacitor bank This stores 10 kJ for explosive and magnetic effects

Time to get serious! A capacitor bank like this stores electrical power which can be released very rapidly. For example the two grey capacitors previously provided power to pulse a laser in the “Star Wars” program. “Continue reading” for more details and photos. I have used these for effects such as: Exploding stuff Lightning Simulation. Intense light pulses Serious can crushing

Exploding wires Coin shrinking Think of a popped balloon releasing a few breaths energy in a fraction of a second and you have some idea. The electrical energy can be released in a very small area giving transient but huge powers for heat, light or magnetic fields. Total stored energy with all charged to capacity is 10 + 10 + 8 = 28 kJ. Unfortunately, the voltage ratings are different so they can only be charged to the 12 kV if in parallel but still 16 kJ can be achieved as a paralleled group. To date, I have only charged the capacitor bank to 10 kJ.

Features 215 uF (112 + 51.2 + 51.7), 12 kV max (16 kJ) The caps are all in parallel which limits the voltage rating to the lowest cap ie 12 kV. Minimal conductor length. Total path is 21, 25 and 30 inches for each cap to terminals and back. Inductance is of the setup is 200 nH with a 6 inch straight wire across the output terminals. The individual caps are 80 + 40 + 40 nH in parallel. Resonant frequency is 25 khz (period 45 us) for the 215 uF. it is measured by looking at the ring frequency on the CRO with a small energy discharge into the wire short circuit. Heavy copper bus bars. Mostly 1 1/2 inch by 1/4 inch. Switch is mechanical activated by pulling out a plastic spacer with a string (simple solid and reliable). Spring force is from two bedsprings. Copper braid (2 inch) connects to a copper plate as one contact. Switch contact on coil side is a hinged 1 inch brass rod with a neoprene pad under it as a damper. Contact is solid and does not seem to bounce. The angles will result in a bit of slide on contact. Large wood blocks absorb any force and are braced with the welded can edge rather than the insulator or HV terminal. Terminals are brass but main bolts to case and HV terminal are steel. Voltage measurement is via an analogue meter and 20 Mohm chain. Lights. Flashing neons x 4 with increasing rate with increasing voltage from 250 V to 12 kV. Also single neon that lights with cap voltage down to neon threshhold of 70 V. Discharging is via two 30 k ?50 W resistors. (has to be intermittent due to inadequate rating) Charging through same 30 k x 2 resistors through my MOT supply at present until I get the NST supply running.

The photo above shows the light blue Maxwell capacitor specs. 110 uF, 12 kV, 8 kJ, 75 kg. General Atomics have given the specs as 80 % rated voltage reversal at 100 kA. 75 A RMS CW current. Design life 30,000 shots or 1600 h DC. Inductance 40 nH.
The 2 grey Aerovox capacitor specs. 50 uF, 20 kV, 10 kJ each. They are smaller and despite the higher energy are rated at only 20 % reversal. They were apparently used for ‘Star Wars’ laser work and saw only 2 hours service in the 1980’s. These are all proper energy discharge capacitors with low inductance low profile, high current terminals. They are all second hand so remaining life is not known. I built the special trolley for it to accommodate various experiments as 195 kg is just too much for me to lump around. The total energy able to be stored of 28 kJ can be compared with the kinetic energy of an AK-47 bullet of 2 kJ in flight. An exceptional level of care is required to avoid unintentional discharge in close proximity in view of the extreme sound / flash / EMP levels. Also metal fragments of exploding coils are of high velocity and very capable of injury. With these I hope to be able to do a variety of interesting things such as extreme can crushing, coin shrinking, exploding wires, and projectiles as well as a couple of interesting pulsed Tesla coil experiments. A 1 kJ shot at dusk to get the exposure long enough so I could coordinate a pull on the string and take the shot.
The right photo shows the gap wear is fairly mild but I have only had a few shots at 4 kJ max at this stage. Still so sign of failure or problems so should handle higher powers yet. Peak current was 70 kA so far. Actually there is surprisingly little black copper oxide charring. I attribute this to the hard positive contact with slide but little bounce. Note the nick in the braid from an exploding coil (or the aluminium tube as it disappeared down the wormhole portal). I am still using the same switch and contacts 4 years later in 2014 so it has been durable and reliable.