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4hv.org :: Forums :: Electromagnetic Projectile Accelerators
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Portable 1.25kJ coilgun finally done

Author Post
Saz43
Wed Sep 15 2010, 07:45AM Print View
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 292
Hey everyone!

I've been working on this project on and off for over 2 years now, interrupted often by school, frustration, and also general laziness. But after a solid summer of late nights in the garage, and tons of support from you guys, it's done!

It's a fully portable, NiMH powered, ZVS charged and SCR switched single stage design. The overall goal wasn't efficiency or to successfully employ any clever tricks, but rather to see how thick of an object I could blow a hole through with a hand held gun. The mechanical design was optimized to be lightweight, compact, and easily accessible for maintenance. Electrically, I tried to keep things as simple as possible. The gun centers around Uzzors2k's ZVS capacitor charger, found here: (Uzzors, you are the man).

Here are some specs:

- 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: 1.248kJ
- Switching: one massive stud-mount SCR
- Clamping diode: NONE- charger output bridge rectifier takes care of this
- Barry's sim puts the discharge at a peak of 4.6kA with zero crossing at 2.68ms.

Here's a video with an technical overview and of course plenty of carnage:

And a photo album showing the finished product:

**Update: Photobucket bandwidth blown, pictures in video form here:
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GhostNull
Wed Sep 15 2010, 08:45AM
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
Very nice! Good work! =D

Edit:
Your design is very neat and compact
I see you made some diagrams for your coilgun (pics at end of video)
Could you post them please?
They would be useful to other people to see how such a neat coilgun is made and designed. =D

Thanks!
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Torchwood
Wed Sep 15 2010, 03:27PM
Registered Member #2668
Joined: Sun Jan 31 2010, 12:11PM
Location: South Australia
Posts: 18
Very well done, I am impressed, design, looks, performance and style!

So what movie will this be appearing in?
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Saz43
Thu Sep 16 2010, 09:41AM
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 292
GhostNull wrote ...

Very nice! Good work! =D

Edit:
Your design is very neat and compact
I see you made some diagrams for your coilgun (pics at end of video)
Could you post them please?
They would be useful to other people to see how such a neat coilgun is made and designed. =D

Thanks!



My pleasure.

First, everything is laid out and wired together on a test-bed (I managed to break a window since this was flimsy).

Here are some gun drawings. You'll notice that I went through several design iterations before I came to something I was happy building. Some elements from each design made it into the final build.

Since the whole design is built around the charging circuit, it was carefully laid out to-scale on graph paper before being soldered together.

Here is the preliminary design on the barrel mount and SCR housing.

This shows the mechanical construction progress. Everything was based off of the scale drawing to make sure that each piece was cut and assembled properly.

This shows the electrical systems coming together. Note that there is a layer of packing tape between each coil layer to provide cohesion and insulation, and the the final coil is heat-shrink-tubed for safety and protection.

Just for fun, here's my "lab" , and here's my PSU for the testbed , built just for this project.

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GhostNull
Thu Sep 16 2010, 10:15AM
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
Great! I've uploaded the photos so they never become broken links =)
Saz43 wrote ...



First, everything is laid out and wired together on a test-bed (I managed to break a window since this was flimsy).



Here are some gun drawings. You'll notice that I went through several design iterations before I came to something I was happy building. Some elements from each design made it into the final build.



Since the whole design is built around the charging circuit, it was carefully laid out to-scale on graph paper before being soldered together.



Here is the preliminary design on the barrel mount and SCR housing.



7 This shows the mechanical construction progress. Everything was based off of the scale drawing to make sure that each piece was cut and assembled properly.



This shows the electrical systems coming together. Note that there is a layer of packing tape between each coil layer to provide cohesion and insulation, and the the final coil is heat-shrink-tubed for safety and protection.

Just for fun, here's my "lab" (below), and here's my PSU for the testbed (below), built just for this project.




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Barry
Thu Sep 16 2010, 01:11PM
Registered Member #90
Joined: Thu Feb 09 2006, 02:44PM
Location: Seattle, Washington
Posts: 296
Very nice job! Well done, and even the video looks very professional.
Thanks for the credits at the end, I am touched!

Cheers, Barry
They keep asking me "Paper or plastic?" So I answer, "Either one, I'm bi-sacks-ual."
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woxxey
Thu Sep 16 2010, 03:26PM
Registered Member #1906
Joined: Sat Jan 03 2009, 05:06PM
Location:
Posts: 39
Now that's one good looking coilgun! And judging by the video it seems to be performing quite well as well.
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TechNerd
Sun Sep 19 2010, 01:19PM
Registered Member #2289
Joined: Thu Aug 13 2009, 02:49PM
Location: Jylland, Denmark
Posts: 17
Awesome job... very impressed indeed.. :D
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Uzzors2k
Sun Sep 19 2010, 02:26PM
Registered Member #95
Joined: Thu Feb 09 2006, 04:57PM
Location: Asker, Norway
Posts: 1306
Dude, that's so cool! I think this is the best portable coil gun I've ever seen. The bodywork is amazing!
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Saz43
Wed Sep 22 2010, 07:39AM
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 292
Pictures saved in video form due to bandwidth limit on Photobucket:
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GhostNull
Wed Sep 22 2010, 08:15AM
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
Your video has got +112,276 views in one week! Nice! This thread has also got a ton of views.

Great work! This must be on some site somewhere. How about you submit it to Hack A Day?
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DerAlbi
Wed Sep 22 2010, 05:47PM
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 100
"Must be on a site somewhere"

Good design attracts veryone.. Good electronics attracts just us here...

Btw: i would really love to get some numbers from this design.. I am interested in efficiency and velocity and projectile energy and so on.. this is data that is not accessible.. I think this should be more important than good looking photos.. or at least equal important.. i hope this does not make me an outsider

Greetings
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rp181
Wed Sep 22 2010, 10:42PM
Registered Member #1062
Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1527
Great Job!
Especially with making 4 of those large capacitors look so small.

Are you holding the capacitors by the screw terminals? I would add more support if you are. The 400v 3900uf capacitors don't have the best attachments.
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Saz43
Thu Sep 23 2010, 06:41AM
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 292
GhostNull wrote ...

Your video has got +112,276 views in one week! Nice! This thread has also got a ton of views.

Great work! This must be on some site somewhere. How about you submit it to Hack A Day?


I sent it to Hacked Gadgets, and from there Gizmodo and PopSci picked it up. I think popularity bubble burst already though, since today had only half as many views as yesterday.

DerAlbi wrote ...

"Must be on a site somewhere"

Good design attracts veryone.. Good electronics attracts just us here...

Btw: i would really love to get some numbers from this design.. I am interested in efficiency and velocity and projectile energy and so on.. this is data that is not accessible.. I think this should be more important than good looking photos.. or at least equal important.. i hope this does not make me an outsider

Greetings


Too true! My electrical engineering really isn't too extraordinary, it's a very simple design. I think it's the video-game look that's gotten the attention.

Sadly, I don't have THE most important numbers- projectile velocity and overall efficiency, due to a lack of funding for a chronometer. But since I start work in a few weeks, I promise I'll have those numbers for everyone ASAP.

rp181 wrote ...

Great Job!
Especially with making 4 of those large capacitors look so small.

Are you holding the capacitors by the screw terminals? I would add more support if you are. The 400v 3900uf capacitors don't have the best attachments.


For the most part they are just held on by the screw terminals. But there's enough friction with the body work that when I unscrew one, it takes a good bit of force to pull it loose. Thanks for the warning though, I am somewhat paranoid of getting electrocuted.
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DerAlbi
Thu Sep 23 2010, 08:51AM
Registered Member #2906
Joined: Sun Jun 06 2010, 02:20AM
Location: Dresden, Germany
Posts: 100
The easiest way for you to detrmine the velocity would be that you place 2 sheets of paper in a distanace of 1..3m. Then you can record the sound with a simple microphone that is in the middle of these papers. If you shoot, and you samplingrate of your recording is high (96kHz?) you should be able to see the shootthroughs in the waveform Should be quite easy for you.. its doable with a headset afaik.

The mass of the projectile could be determined by volume*density. Volume of an irregular body is easyly determined by how much water rises in a measuring cup..

If you spend so much time, take these 10min too

Greetings
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pepsi2451
Thu Sep 23 2010, 07:32PM
Registered Member #3234
Joined: Thu Sep 23 2010, 07:19PM
Location:
Posts: 1
Very cool! I wanted to make one a couple years ago and never found time to get started. After looking around this site, I might have to finally give it a shot.

For the velocity, have you thought about posting on a firearms forum? I don't know where your located but most reloaders will have a chronograph and a reloading scale. I'm sure someone in your area would let you use theirs, just post up that video.
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GhostNull
Fri Sep 24 2010, 01:16PM
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
For anyone setting out to build a coilgun I strongly recommend you vist: and READ READ READ

Coil guns aren't techincally firearms as they do not use an exsplosive force to propell a projectile.
Coil guns are also pretty impractical, a bow and arrow would likely have more power than a coil gun. Coil guns are just something you build for coolness and learning
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Killa-X
Fri Sep 24 2010, 03:05PM
Registered Member #1643
Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1036
Nice design! Never fear those capacitors ever risking a possibly explosion I take it? I like the small compact design, looks really good!

I plan to make one, like your voltmeter on the side! I plan to do a 980Kj coilgun. I have 800v 300A stud diode and 1200v 650A scr. Should be good!
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Saz43
Sat Sep 25 2010, 05:01AM
Registered Member #1525
Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 292
GhostNull wrote ...

For anyone setting out to build a coilgun I strongly recommend you vist: and READ READ READ

Coil guns aren't techincally firearms as they do not use an exsplosive force to propell a projectile.
Coil guns are also pretty impractical, a bow and arrow would likely have more power than a coil gun. Coil guns are just something you build for coolness and learning


Wow, thanks. Hopefully people will come here and read this. I should have put that on my video description- most people don't understand that and are all like "LUL UR T3h suck cuz I could doo more damage with a (instert whatever here)".

Killa-X wrote ...

Nice design! Never fear those capacitors ever risking a possibly explosion I take it? I like the small compact design, looks really good!

I plan to make one, like your voltmeter on the side! I plan to do a 980Kj coilgun. I have 800v 300A stud diode and 1200v 650A scr. Should be good!


Nah they won't explode, not unless I hook the charger up backwards somehow. I hope you mean 980J, cus 980kJ is bigger than the deadly-weapon coilgun the army built and would certainly blow your SCR to pieces. But none the less, best of luck on your project!
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Induced
Sat Sep 25 2010, 10:14AM
Registered Member #3011
Joined: Sun Jul 18 2010, 11:33PM
Location:
Posts: 9
sweet ghetto blaster Saz. I love it.
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GhostNull
Sat Sep 25 2010, 11:29AM
Registered Member #2648
Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291
@Saz43: I got a couple spelling errors there and I would be more worried about an flux of 7h3 1337 n00bz >.>
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ben5017
Thu Oct 14 2010, 09:34PM
Registered Member #3315
Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 138
can you please explane how u made the flyback transformer? how do you know haw many winds to get the correct output voltage.
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happyp
Mon Apr 23 2012, 09:36PM
Registered Member #4561
Joined: Mon Apr 23 2012, 04:18PM
Location:
Posts: 3
I am creating a coil gun using a capacitor bank consisting of 3 470uF capacitors rated for 500V. They charge to about 250V using a Cockroft -Walton voltage multiplier. A switch controls the amount the capacitors are charged and a voltmeter gives and accurate reading of the current voltage of across the capacitors. An SCR is in place to control the triggering of the gun, but is being shorted at the moment to test. The coil specs are Inductance = 0.673mH, Resistance=1.3 Ohms, 412 turns, 4 layers of 103 turns, 22 gauge magnet wire, turn density of 14.8 turns/cm, wrapped around a copper pipe. I tried firing a bb and it didn't even move. I'm assuming there isn't enough current flowing through the coil, and i tried using a pvc pipe instead and was still unsuccessful. Help please
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Pinkamena
Tue Apr 24 2012, 07:26AM
Registered Member #4237
Joined: Tue Nov 29 2011, 02:49PM
Location:
Posts: 112
Very nice design!
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Krautesh Vakir
Sat Sep 01 2012, 06:05AM
Registered Member #6214
Joined: Thu Aug 16 2012, 08:49PM
Location: New Zealand
Posts: 2
Wow awesome work, I had never heard of coil guns untill I randomly came across the video for your project while looking for something else. I'm definitly gona look into having a go at making one of these. *starts reading coilgun info for dummies*
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