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Coil Cannon Donation?

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LAN_403

MScooling

Fri Sept 21 2007, 09:08PM

Registered Member #1016 Joined: Fri Sept 21 2007, 08:46PM
Location:
Posts: 19

I used to post here a few years ago. I have a "coil cannon" as I like to call it. Details on it can be found here:

So here's the deal. It's been sitting in my basement for over 2 years collecting dust. I have put in at least $500 into the project, but at the moment it is just wasted potential. My passion for EM weapons has moved onto something else, mainly making my car faster :P I might be willing to give it away to someone on 4hv. So here's you're chance to score some decent EM weapon parts if you can convince me to make a donation. Post your resume.

Ragnarok

Fri Sept 21 2007, 10:23PM

Registered Member #659 Joined: Fri Apr 20 2007, 09:14AM
Location: SW Hertfordshire, UK
Posts: 75

For some reason, I looked at the title, and read "detonation". I've really got to get out more and play less vidja games.

I'd love such a thing, but there are three main problems. Lack of experience (I try to compensate with careful enthusiasm), country of residence (UK), and storage space (I'm a student engineer, and my room is not very generously sized.).

But, nonetheless, very impressive piece of kit. I'll envy whoever ends up with it in the end.

...

Fri Sept 21 2007, 10:26PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Wow, I could never imagine giving something like that away!

I am sure I could manage to get him working, IIRC you managed to get all of the stages working (and they don't even blow up the diodes anymore!), and were just working on getting the stages to fire at the right time?

Where are you located?

Edit:
Looking at the old build thread, I think some of the coils need to be rewound, and the bank rewired for 900v. You had a bank that was 1.5Kj/450v, and the coils were about 1mH and .01R of resistance. That would give a current peak at 20ms, and won't be back down to 0 for abotu 50ms. Over a 1ft long coil, your 'ideal' velocity would be like 20ft/--so unless you are shooting bullets a foot long your efficiency will suffer.

If you are shooting a 25g projectile (rough guess by the picture of one sitting next to a AA battery), have 5Kj going in, and are aiming for 5% eficiency, you would be be able to get 500ft/sec out of it.

Likewise, the last stage (assuming constant velocity for simplicity) would need to have a pulse 2ms long, which will need some work.

I am thinking the best solution would be to rewire the bank (at least for the last stage) as 3.5mF/900v, and using a much smaller coil-something along the lines of 100-200uH And with a total ESR in the 100mR range... The SCRs should still be fine, as the current should stay nice and low at arround 3Ka. Might need new diodes though to handle the higher voltage.

BTW, here is my coilgun

MScooling

Sat Sept 22 2007, 12:03AM

Registered Member #1016 Joined: Fri Sept 21 2007, 08:46PM
Location:
Posts: 19

It is hard giving away something I put so much time and money into, but if there is a chance someone could get this project working, I would be more than happy to see it happen.

Every time I see the coil gun, I keep telling myself to finish it. The problem is that it should have been finished a long time ago, but I stepped up it's complexity far beyond my skills.

I'm also an engineering student. I was once working toward EE, but a few years ago switched to Mech engineering. I live in Virginia and I'm a student at Va Tech.

...

Sat Sept 22 2007, 04:03AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Well I can't guarantee that I will get it working any time soon (especially considering that I have a 20w yag laser on the way), but I am sure that I would get it working sooner or later... definitely be the end of the school year.

I have room to store it, and all of the equipment and probably most of the parts that would be needed to get it working reasonably well. And a yard that is 300ft long to shoot in in

Right now I am only a Sr in high school, but I have been doing EE for years now, and hopefully next year I will be doing it at UC Santa Barbra. heh, even before I got out f my sophomore year I was offered a a job at the company I intern at (which builds mostly solar cells, and semiconductor lasers, but the part I work for builds bomb detectors) to do EE work for one of the guys working there

By the way, how heavy is thing thing? I can't afford $500 to get him shipped over here...

since you asked for it here is my horribly outdated resume

MScooling

Sun Sept 23 2007, 01:56AM

Registered Member #1016 Joined: Fri Sept 21 2007, 08:46PM
Location:
Posts: 19

I will be home in 2 weeks and I will pick the gun up and bring it back to school. I think I may have to sell the capacitor bank... my car got towed last night so now I'm out $150.

It would be cool to see the gun working, but if you can use the SCR's for some other HV project, by all means use them.

The gun itself without the cap bank weighs around 30 pounds due to the copper coils. I shipped a set of 70 lb. cast iron cylinder heads a few weeks ago for $55 via FedEx ground.

...

Sun Sept 23 2007, 02:13AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Hmm, the gun would be a bit trickier to get working sans cap bank

I have about 1.5kj of caps on hand, I suppose I could get it working using them (abit at a fraction of its designed output power). But it would be such a shame to see such an amazing gun be thrown away!

I don't think there are a whole lot of other things that us hobbyists can use massive SCRs for, mainly because they are slow and can't be turned off. Unless of course you have a 1000A feed to your house and can use them as they were supposed to be used

phil

Sun Sept 23 2007, 03:11AM

Registered Member #314 Joined: Mon Mar 13 2006, 03:12AM
Location:
Posts: 52

Wow i would love that thing, however i lack the resources and knowledge to get it working at this time. ... knows his stuff so he could make better use of it. But man could i piss my neighbors off with that lol.

Plisco

Tue Dec 11 2007, 03:41AM

Registered Member #1119 Joined: Wed Nov 14 2007, 09:15PM
Location:
Posts: 9

I'm not anywhere near any of yall in my knowledge of EE and electromagnetics, but im learning, and id love to get my hands on that to learn with and eventually get it working. I actually live down in hampton roads, so maybe we could cut out all the shipping costs.

FastMHz

Tue Dec 11 2007, 08:47PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

My my....that's a NICE gun! I'm already quite buried under projects though

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