Thursday, September 23, 2010

Daily Shot of Homemade Coil Guns!

Ok, this video is amazing!  If you thought the mini cannons were cool - check this out!  Technical specs and links after the jump!

By the way - if you like investing information, check out my other blog! 

After 2 long years of on-and-off work my coilgun project is finally completed. For anyone who doesn't know what a coilgun is, it's a gun that fires a projectile with magnetic force instead of gunpowder. The projectile from this gun won't kill a person, but the electrical energy stored in the capacitors is 78 times the lethal amount for human beings so this is no toy.

Some technical data:

- Action: single stage, bolt
- Power supply: 12V NiMH battery (fires about 15 times/charge)
- Charging: 40 watt regulated ZVS flyback driver (charge time ~30s)
- Capacitor bank: 4x 3900uF @ 400VDC
- Stored electrical energy: ~1.25kJ
- Switch: SCR
- Efficiency: unknown, probably 1-3%
- Body: lightweight ABS plastic pipe and sheets


***Answers to commonly asked questions***

Q: What is the projectile speed/energy?
A: I don't know yet. I'll post what it is once I have the equipment to measure it (speed trap, scale).

Q: Will a smaller projectile result in better efficiency?
A: No, a smaller projectile won't be able to absorb as much magnetic flux as a larger projectile, due to a phenomenon known as magnetic saturation (Wikipedia it!)

Q: Will multiple coil stages improve power/efficiency?
A: Yes! I only have one stage on this design for the sake of simplicity.

Q: Will rifling in the barrel improve accuracy?
A: No- not at these projectile speeds. A projectile has to be moving at a certain speed before rifling is effective.

Q: How do you claim 1.25kJ of energy?
A: 1.25kJ is the electrical energy stored in the capacitors, according to the equation E = 0.5*C*V^2. For this gun, C=15600uF and V=400V, thus E = 1248J. One of the main drawbacks for coilguns is EFFICIENCY, which, for single-stage hobbyist designs (like mine) is limited to about 3%. So if we assume a 3% efficiency, the kinetic energy (delivered to target by projectile) is in the area of 37J, which is much more than a bb gun but much less than a real gun. I don't have the equipment to measure the exact kinetic energy, but as soon as I do I will report it. Thanks!



  1. I tried to find it.. please find a way to upload.

  2. Ok, I finally got the code working - the default one YouTube was giving me was broken >.< Let me know what you think!

  3. Give two of those to a midget, and we have a mini rambo!

  4. These posts have my juices flowing... i think ima make me one of these!

  5. What in the world, that shit is awesome. I like how it's just some dude in his living room lol.

  6. seen this before. stuff is awesome!


  8. Holy shit, that's fucking awesome!! Totally want one of those things!!

  9. Haha wow, that's awesome. I want a coil gun.

  10. It looks way cooler than what it actually does, like something out of Starship Troopers

  11. That's pretty cool. Looks pretty complicated to make yourself though. I'd end up zapping myself to death or something.

  12. That's pretty sick. I'd end up killing myself lol.

  13. come over man, they are partying like hell already!! >=(

  14. WOWOWO! That was freaking absolutely freaking awesome!!!