Coilgun!!

[Rumdog]

http://www.youtube.com/watch?v=7LjnhhtHojM&feature=player_embedded

[AndyKunz]

That one's pretty low-powered.

Andy

[ron1950]

does his mom know he destroyed her stuff with it? lol

[m4a1usr]

You know the weird part is this is not classified as a firearm. Yet it performs quite well sending a projectile down range. Dont poopoo this to much. It has merit for those dangerous to society. Its not mega powerful, but the irony is its about utilizing energy. Someone intent on constructing a much more powerful version is not going to have to spend 100k for one that in a 1000 times more powerful. Rail guns are simple. Other then the mechanical components they are quite silent. And they are accurate.

Its amazing that there were so many videos of folks constructing these devices. Very interesting. I had no clue?

John

[Rumdog]

I believe it would be much easier for someone who is a danger to society to acquire a actual gun than to build one of these. They are pretty dang cool. This was the first vid I saw.

[AndyKunz]

I don't know, Sten's were made in small shops and in homes.

Andy

[H2OCamel]

now .....how to make it power a saw boat? ;-)

[NativePaul]

Yes, my granddad was doing a job that prevented him from joining up as he was needed more at home making replacement rectifiers for bombed out power stations, but he was in the home guard and made Sten guns at work of the books in his lunch break the barrels weren't rifled but from what I hear they were still plenty good enough for guerilla style street fighting, he made enough for all the home guard in his town and in the end was giving them away to neighbouring towns, I think Hitler would have had a nasty surprise had he managed to invade.

Back to the subject of railguns, it is something that interests me, but having a single coil seems like cheap and nasty way of doing it, and having a series of coils accelerating the projectile along the barrel would be much more effective, it seems like it would be easy enough to have a series of coils with hall effect sensors in front of them to switch off the preceding coil and switch on the next one as the projectile passes it and it would allow easy manual tuning by moving the sensors, but I know little about electronics and have no idea if hall effect sensors and the associated gubbins are fast enough to accomplish such a feat or whether you would have to rely on timers firing the coils at set intervals and laboriously tuning the timing of the intervals to get all the coils firing just before the projectile gets to them.

[osprey21]

You know the weird part is this is not classified as a firearm.
John
A firearm, by definition, is a device that launches a projectile through a controlled explosive charge.

[AndyKunz]

If you're a convicted felon, archery is considered firearms. At least in Virginia.

Andy

[NativePaul]

Andy, calling a bow a firearm stretching the definition to past breaking point to suit the law.
Being an electronics guru do you have any thoughts on using hall effect sensors to trigger a series of coils? I was hoping for you to chime in on that.

[AndyKunz]

Yeah, we used to kid him about having jump down out of a tree with a pointy stick to go deer hunting now :)

No need to use a separate hall sensor. As the round approaches each coil, the round itself will change the magnetic field in the coil. Just like the back-EMF that runs our sensorless motors (on a much smaller scale). It can actually be made to trigger each phase of the magnet as the round travels down the barrel.

Andy

[Kevinlei324]

Does anyone want to build one? I actually have huge capacitors you can use make one:
450v 4700uf. That's about 475 joules each.
I made a couple, but never got around to using my big ones (too scared to).
Will trade for boat parts. LOL