Coilgun

Not so long ago, I attempted to build a magnetic coil gun.

For those of you who don’t know what that is, it’s basically an electrically powered magnetic weapon that uses an electromagnet to propel any type of ferrous metal.

Here are some links:
www.coilgun.eclipse.co.uk...
www.oz.net...

Anyway, I eventually succeeded in building one. It ran off a wall socket which (here in South Africa) is 240V.

Although it was a fun project, I now have suddenly felt the urge to build a better and improved rifle-type model and I wish to bring a few problems that I had in the past to my fellow ATSers attention and hopefully some of you can tell me where I am going wrong.

The main problems of my v1.0 coil gun
• The electromagnet (wound around the barrel) gets extremely hot. I substituted a glass tube that I found lying around however there was a huge loss in barrel length
• I tried to charge capacitors using the mains however when I attached them to the gun, they did not discharge. (This is my main problem PLEASE someone help me!) They did when I short circuited them with a screwdriver however.
• The gun was pretty powerful at short range (could go through an empty coke can) however did not go very far long range. I thought of extending the barrel or using multiple capacitors (if it wasn’t for the above two problems)
• The gun wasn’t portable ( thought of making cartridges consisting of capacitors but due to my second problem I couldn’t)

So, does anyone have any ideas on how I can solve my problems or add to my next gun?

Here's a site with a few portable design's www.pskovinfo.ru...

Please be carefull trying to short out a capacitor with a screwdrive... damn your crazy

Yes ive been to that site before.

Any ideas why the capacitors didnt discharge when connected to the gun though?

Not really sure... how do you have it setup to discharge? It could probably just be faulty wiring.

Just both ends of the electromagnet wired to the capacitor.

Are you sure the capacitor is fully charged prior to connecting it? I wonder also, upon connecting it could it be discharging prematurely...

No it was definatly charged because I could discharge it by shorting it. I dont know about prematurly discharging it tho. Probably not though. When the slightest bit of current runs through it, it buzzes and heats up. It didnt do ANYTHING when i connected the capacitor to it

well, if your equipment is getting hot, I'm led to believe there may be some poor wiring involved. I'd suggest using a series of relays or better yet FETs as switches in connecting capaciters to the coils. And if possible, limit each cap to just a few of the coils, so your end coils aren't trying to draw off an expended charge.

Plugging a coil not meant for 240V into 240V AC for even a second is a sure way to get it hot (not faulty wiring). What are the specs for the capacitor as thats VERY important? I would use a 5 amp 600V diode bridge rectifier, a 450V 200-1000uF electrolytic capacitor with no internal/external resistor. A big 500Amp 600-1000V SCR would be great for triggering the coil.

Or you could use 4 or many more disposable camera circuits with their capacitors wired in parallel (they have to be the same circuits - look exactly the same).

which brings us to the next question, what is your activation? Are you just throwing a switch or attaching a wire to fire the device, or do you actually have a series of coils being electronicly controlled?

I'm also wondering, if you're using some kind of electronic triggering for the coils, what is the basis of your timeing? (leaving the coil turned on after the projectile arrives will slow your projectile.)

Just a push down button. those big heavy duty ones they use in factories, etc. I had to use something like that (while not using capacitors) otherwise the magnet draws my projectile to the center and keeps it there.

[edit on 11-1-2006 by SecretMuffinNinja]

This is not very wise on my behalf but by looking at what you could have made (judging from the picture) you need to compress it all into a rifle.
The overheating problem can be solved by use of a fast cooling liquid whatever that may be.
You need to have a powercharge that can feed from a battery pack that is lightweight on you back DIRECTLY into the weapon itself.
You need to focus more energy to the projectile itself by guiding more power to it. In short more velocity.
You need to use a standard projectile (go get a 7.62 round without the case) and be able to have a feed of it so you can go single or full auto.
Turn the button into a rifle trigger (go online, find parts and get them then figure out how to rig it)
Change the kind of power you use and make sure its a steady pulse that wont drain your battery but will provide you with what you need.
Create a barrel thats made out of heat resistant materials or at least use a barrel thats coated well.
Create a chasm so the cooling liquid can quickly go from the barrel to a cooling chamber (kind of like on a nuclear reactor)
Try and create a "power up" charge that will create a high energy buildup then have a discharge so it will fire (slowly but high enough a volt to get the job done)
Thats all I am going to say from here on out on this subject.