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  • 06/27/2008 (1:00 am)

    24,000j Capacitor Discharge System by

    Filed under: FM_Projects ::

    In the past I’ve been launching "rockets" via induction pads, and a bunch of other discharge experiments at 3500j of energy…the science, videos and some numbers can be seen throughout this site. Now I’m building a much more massive system of ~24,000j of energy. Induction launchers, coil guns, rail guns, etc etc etc can be scaled way up with this amount of energy. I’ve finally gotten all the main bus bars on the capacitors….this bank will be configured for 4500v @ 2400uf.

    I need to score two identical MOTs…I’ll be hooking the primaries in parallel inverted phase, and series the secondaries, giving me the necessary voltage to charge to 4500v.

    Next I need a safety discharge, and to build the remote controlled main discharger, which will be mechanical….SCRs of this size would be prohibitively expensive and/or impossible to get.

    Finding parts will dictate how fast this project comes together, unfortunately…here’s the bank as it stands right now:

    This thing will be remote control and mechanically triggered…I don’t want to be near whatever is hooked to it! I’m thinking giant copper rod, spring loaded, with a release pulled by an RC servo that I trigger via remote control. The giant spring will pull the rod into a giant copper plate to complete the circuit.

    The caps are wired this way because it was cleanest, and they are 10 separate banks of 10 in parallel (each string weighs a ton, and I’m not a huge person to lug a massive bank around, so 10 sets are good for me!!). This gives ample flexibility, though with induction large capacitance isn’t very useful since the platter is far away rather quickly and all extra energy is wasted…so I figure more volts, less uF, so it’s a really short, HUGE pulse….I suspect my first few coils might detonate until I figure out how large they must be to absorb this much energy. I’m also thinking coin shrinking might be in my sights!! To give an idea of just how BIG this is…

    Jan 02, 2008 Update: I’ve found and ordered two identical 1200w MOTs for charging the bank. I have diodes already, and will construct the charging system soon. I’ve also been asking around about discharge systems for such a huge amount of energy, and have settled on an open-air thyratron, aka triggered spark gap using a high voltage plasma. Essentially, a gap is created and a high voltage lightning bolt is created between the gap thus closing the circuit to discharge the bank. I have the remote control unit already for activating the discharge. It now appears that I have almost all the major components!!!

    Jan 20, 2008 Update: The capacitor bank has been completely bussed together for the first time!!! The system, including charger, went “live” yesterday for the first time, charging to 1% of the total energy capacity.

    Jan 28, 2008 Update: I’ve built the charger into a self contained unit, with integrated cooling to keep everything operating at peak performance. I’ve also thought up a way to safely discharge the bank without having completed my pulse discharge system – I bleed off each string into a MOT secondary. It discharges slowly and completely this way. I have charged the bank up to 10kj so far in test charging, and discharged it in this manner. With the charger now a self contained unit, I intend to charge the system from a safe distance, in addition to the previously planned remote discharging. Components fail…bad things can happen…think about this for a second:

    A defibrillator is the device used by medical personnel to start and stop hearts…the typical unit delivers a maximum pulse of around 300j. To give some perspective, my capactior bank would be equivalent to 80+ defibrillators connected AT ONE TIME. But the end result would be worse than that scenario, as all the energy is delivered in one small area with mine….in other words, this bank is deadly, and utmost safety precautions must be taken at all times!!!

    I’m not only worried about accidentally coming into contact with the bank, but the shock wave from a failure/component detonation could also be deadly. With this in mind…I intend to only fully charge this behemoth from a distance!!! This is a HUGE amount of electricity!!!!!!

    Apr 21, 2008 Update: I’ve been out of action for a while, as I have just moved. I now have more space and freedom for my experimentation 😀 The discharge system is finally all set up and operational, and additional construction and experiments will resume shortly!!

    Jun 27, 2008 Update:The entire system has now been completed….my full size triggered spark gap works like a charm. I have successfully discharged 22kj of energy into pickles, potatoes, soda cans and more – with rather explosive results. I plan to build a 1 foot+ diameter pancake coil with flat transformer wire soon to launch EM Rockets and other large projectiles.

    I did destroy my coilgun though…The coilgun was so powerful at 3.8kj that it shot a slug through both sides of a 5-gal pale and almost through sheet metal behind it!!! So I decided to try 5kj…and it detonated.

    And this is the new 11″ pancake coil made of 1/4″ wide flat transformer wire. It launched a 3ft x 1ft x 1/8″ thick sheet of aluminum half way to the garage ceiling with only 300j!!!:


    6 Responses to “24,000j Capacitor Discharge System”

    1. stalkersas Says:

      MAAAN that’s huge, i can’t w8 to se some experiments with it XD

    2. twentyonebravo Says:

      You know…if all I got for Christmas was one lousy video of this firing…well that’d still be ok. In fact, that’s all I really want. So basically, it’s up to you to save my Christmas. No pressure.

    3. Vector Says:

      Many years ago (about 40) I played around with a cap bank for electrical fishing, nowhere near as potent as this baby. I used a plasma unit to discharge the caps – two copper plates mounted about 25mm apart in a milk bottle which I evacuated with a simple mechanical vacuum pump. Also had a trigger electrode between the plates. When a trigger voltage (from a car coil) was applied the gas in the bottle ionized and allowed the current to flow between the plates. Maybe you could try something similar.

    4. terramir Says:

      Looks like fun, I’m just worried if I build something that big I’ll accidently create an Em pulse that wipes out the entire neighborhoods cars computers tv’s etc.
      I myself am building a capacitive spot welder for battery tabs, so be run off my solar battery bank (yeah I got solar panels on the roof, in los angeles, living in an apt. LOL got a problem with SCR triggering it’s draining my cap to much to weld properly. check this schematic out pl0x if ya got some time. it’s the welder PDF file I like your motto use what I got (hmm I got plenty of 2N2222 or MPSA25’s and lm317’s if I could trigger them both off the foot switch, and use my power supply to trigger the SCR it would be great, maybe then I’ll get some decent welds :(

    5. Trike Says:

      I have got to try this!!!

      Been an Electronics Tech a long time, but never had this kind of fun! I’m willing to handle the liability thing, can you provide a starting circuit for me to build around? I have a project in mind for once its up and the bugs worked out, a launch system to put my model sounding rocket in the air and moving, before the actual rocket engine fires. I’m even working on a ‘crush’ system to prevent my rocket looking like the bottom of yours! Sort of a dummy stage to take the abuse instead. Look forward to hearing from you on this.

    6. FastMHz Says:

      It sounds like you need an induction launcher :-) I’ve had others suggest using the electrical propulsion to get a chemical rocket going as well, however the major problem always is the self destruction because the electrical part accelerates the rocket so fast. I actually have a schematic and datasheets for my 3.5kj launcher on this page:

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