Instructables
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Learn how to make a simple coilgun using only a few parts that are fairly easy to obtain. Be Willing to spend more than a week on this and you might need a few heavy power tools (Only to make good projectiles). I built my first one in only a week after I had all the parts.

Coilgun Principal:
Coilguns(Pulse Accelerators), like railguns(Linear Accelerators), use intense electromagnetic fields to propel objects at incredible velocities unreachable with modern gas driven weaponry (given enough stored energy of course). This coil gun is known as a reluctance coil gun. The coil uses its electromagnetic field to pull a ferromagnetic (magnetically affected) projectile, in this case a shaped steel round, toward its center. Ideally the current supporting the electromagnetic field will turn off when the projectile is in the center allowing the projectile to continue traveling down the barrel, out the gun, and to the target. Use a coil and a few batteries to understand the properties of this system better. Many coilguns incorporate multiple stages at lower energy levels as efficiency tends to die off as more Stored Energy is used for a single coil design. For more information go to step 5.

A basic coilgun operation diagram is included at the bottom.

'!!!!!!Learn More About Coilguns!!!!!!'

What is a relay?? (Elaboration on step 2)

How does it work?
A relay is a simple electromagnetic switch. It uses an electromagnet to pull two contacts of a separate circuit together, completing the circuit and allowing electricity to flow.

What is it used for?
A relay was originally used to allow a machine or computer to switch something on or off electronically. In this application it is used to switch the capacitors energy into the coil.

Why use it?
Relays allow more current to pass through them than regular push button switches, which normally weld together. You can use a very high rated toggle switch for this, but it is usually more expensive and larger than a relay of the same rating.

Part Deals

The Parts You Need Are:

From Radio Shack or Other Electronic Parts Dealer:
-20 or 22 AWG Hookup Wire (Buy both the solid and stranded)(Larger wire is better because it lowers the resistance in the system which increases the coil gun's efficiency)
-22-20 gauge Magnetic Wire (Depending on your coil preference;See step 2)(Radio Shack has a Package with 40 ft of this but I recommend buying it from a different store to save cost and to get at least 100 ft for a coil more than 7 layers thick)
-A Relay (Electronic Switch), Preferably 30 Amps or more (I got a 12VDC/30A SPST Automotive Relay from Radio Shack, but I would recommend a higher voltage and current rating)
-A Momentary Switch( I used the SPDT Switch with 3/4" Roller Lever from Radio Shack, but you can use a lower rated switch)
-An On/Off Switch(I used the DPDT Heavy-Duty Rocker Switch from Radio Shack but you can use a lower rated switch)
-Battery Packs (More than 2 2AA Holders and 1 9V Holder)(The more 2AA Battery Packs the better)( I would suggest getting a few 2 C Battery Holders as they provide substantially more power to the Charger, resulting in a MUCH faster charge time; be careful not to over load your chargers, see last step for safe charger to battery ratios.

From Other Places:
-Used Disposable Camera's (The More The Better as this is the gun's central component), You can get them by asking most photo places like in Walmart or CVS for used disposable camera's. Remember: it is for the batteries, not a gun...never
-Straws from Burger king or local chain(You May use another place's straws but the coil's inner diameter will differ; Of course if you choose a smaller straw a smaller projectile will go faster but not pack as big a punch, AKA momentum)Also,Smaller Straws may be used to place on the back of your projetile for stabilization, this works well.
-Large Nails (3/16 to 1/4 inch Diameter, or bring your straw to Home Depot to fit the right nail)
-A Bolt, two washers, and a nut. (The bolt needs to be the diameter of your straw and the washer needs to fit well and be as wide in diameter as possible)
-A spray paint "can gun" handle or other handle. (I got mine from Harbor Freight)
-Plexiglas, wood, or sheet metal(Optional for gun casing)
-Electrical Tape
-Solder
-Flux (Not necessary, but it does help)
-Super Glue/ Epoxy/ Hot Glue(Used for gun casing)

Tools
-Solderer
-Pliers
-Wire Cutters
-Wire Stripper( A big help)
-Scissors
-Glue Gun( For outer casing)
-Screw Driver(Flat Head)( To get cameras apart and discharge capacitors)

Losing Drive To Build This? Check out The Videos

The PAR-1 video demonstrates the kinetic output of a 12 layer coil with a 470uF 400V(to 450V) capacitor, that's only 50 Joules!.

My Web Page: Future Experimental Systems
Go to see some coilgun and railgun projects of mine.

Finished a coilgun and want to share it? Post it Here: Coilgun Arsenal

Useful Electronic Goods Sites:
- Mouser Probably the best Distributor I've come across, vast selection of items, best pricing for a non-wholesale electronics site, and great navigation and organization.
- Goldmine Great prices on useful parts
- Digikey Good for hard to find parts.
- MPJA Great place to buy magnetic wire and LEDs
- Electrostore Large high voltage capacitors at cheap price and other high power components.
- Surplus of Nebraska Great prices on magnetic wire if bought in large quantities.
- Alltronics An OK surplus store
 
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sunwoongkim16 days ago
rwilsford07, may i ask your email?
Drake23124 months ago

hi uh what kind of capacitor did you use i' new to this so i'm not really sure, i know it isn't a super/ultra capacitor but if you could give me a link to a similar capacitor to the one used in this instructable that would be helpful thanks

knexpert17007 months ago

I think I'll try this project this weekend.

qboid1 year ago
I have got myself two types of disposable cameras (FUJIFILM and Polaroid).
I can't tell where to cut the circuit board (and what the transformer looks like) so that the transformer comes out.
If It's not too much trouble could someone draw on the photos where I need to cut.
Thanks.
IMAG0041.jpgIMAG0042.jpg
qboid qboid1 year ago
The circuit board with the red LED. Do I need to cut it with the Transformer?
qboid1 year ago
When you say the capacitors should be rated 300VDC...
Do you mean each capacitor or all the capacitors in the bank must equal 300VDC to 900vdc?
Beachley qboid1 year ago
Each capacitor.
the design bears striking similarity to that of a high power emp device, will the gun emit an emp pulse when fired? http://www.wikihow.com/Build-an-EMP-Generator - (link to wikihow that shows how an emp device is created)
Brinith1 year ago
Where else can I get charger circuits from? A lot of the stores nearby me are not that generous.
nrickels91 year ago
I'm willing to bet you get better picture quality with one of those kodaks.
andyyudha1 year ago
Hey,I'm use circuit disposable fujifilm,how to make it into parallel ?
So I am looking at the semi automatic design, and I was wondering what exactly the injector solenoid did? Also if I used the "Boost Converter" that he also shows you how to build would you need the disposable cameras?
In reply to ishmal1103:
It's possible you've heated a transistor too much and it has burned out just replace every transistor but be quick and make sure it doesn't get too hot again or it will blow one of them out and then you will have to replace all of them again because you can't tell which one is the dead one (make sure when you get a new transistor its matches the one on the circuit board or it wont work e.g. the circuit board one might be negative positive negative (npn) so you will need to get a npn and not a positive negative positive (pnp) you can search up how to test between the two.
Hey, I recently managed to obtain a few pretty large capacitors (3x 3300uf 350v to be precise) and I was hoping to build one of these, I was just wondering if someone could recommend what size coil I should use and possibly the addition of more stages?
The theory behind coil guns is that they create a large magnetic field momentarily that accelerates your projectile, either through or away from the coil. The strength of the magnetic field is determined largely from two things, the amount of turns your coil has and the amount of power you push through it. You want the smallest wire gauge possible that doesn't liquify under the current you force through them in order to pack as many turns into your coil as you can in a given size.
The overall size of the coil is really up to you. You want the inner diameter to be slightly larger than your projectile. I wound mine around 1/2 pvc pipe and used that as a barrel. I hate supporting Radioshack, otherwise known as "The Man" when it comes to hobby electronics, but they usually sell magnet wire in the back that has a small enamel layer and is perfect for winding coils. Mine was roughly 2" long and only about 1/4" thick but worked great.

Those capacitors hold a lot of energy( E=1/2*Capacitance*Voltage^2 ) just over 600 Joules fully charged by my calculations. A simple design would be to just charge them up and discharge them all through your coil. In order to add more additions it gets more complicated with light triggers and high voltage transistors, but totally possible with something like an Arduino.
mbaker261 year ago
I am having some trouble im trying to do this with an electric weed eater any advice
Jagneeto1 year ago
Is the DC to DC HV Boost converter a substitute for the camera chargers in parallel? Sorry about the stupid question I just want to make sure.
coolkids1 year ago
do coilguns require high voltage or high current
Wow bro, you get everything i use from the same places. CVS 'cause i can ride my bike there, Harbor Freight 'cause they carry everything (including parring knives if i spelled that right and a sextant. and don't forget the machete and foot-long hunting knives!), and Radio Shack for the electrical components.
and just wondering, what would change if you hooked up a 2100v 1uf capacitor to the coil? wouldn't the performance turn out to be better? after all, it is a high voltage capacitor.
Not really if your charger charges at 300v and you have a 2100v cap at 1 uF then the cap will be charged to 300v 1uf you would see almost no change
Oh and the projectile would go much faster
You would need to up the voltage output of the charger bank and beef up all the wires. Maybe add some diodes to prevent blowing the chargers, and do some other things to make it work
Anyone have any ideas to replace the camera charging circuits with something more efficient?
Rebreg nms222 years ago
No unless you can make capacitors ( which I highly doubt) you can get them at Walgreens though.
mintybot Rebreg2 years ago
It sounds like he was talking about the actual circuit that charges the capacitor, not the capacitor itself. I've always wondered about doing this too.
fascinating, amazing how small you managed to make that SDPA-1 model. for simplicity of building would i be better trying to make a coil gun or rail gun? i have used that circuitry from disposable cameras to produce high voltage before but avoided the capacitors as they deliver terrible shocks if you go anywhere near their electrodes. i don't think i would try for making it automatic, that wasn't very clear how, but i might attempt to build one. great instructable.
Ekzile4 years ago
 Is it possible to make one semi-auto or even fully auto? Or does it need to charge before every shot?
It would be semi-auto with this design, however the second shot would need time to charge the capacitors before you got any real distance out of it. Automatic would require straight raw power instead of charging a capacitor bank, in which, the setup here would be fairly useless. If you're thinking about automatic, your best bet would be to try and amplify the current, which would require heavier gauge wires and most certainly would be much more expensive, heavier, and less mobile. Besides, unloading automatically is extremely unnecessary. The only reason to fire anything automatic is in war. Anywhere else, semi-auto is more than enough.
For full auto, just have dual or quad, depending on the rate of fire, that change each shot. So while the recently fired cap bank charges, you fire from another bank. It would be rather bulky, and far more expensive, but not that much harder to do.
Could you please explain how to make the gun alternate between chargers?
Two words Gatling gun.
lol, I shoulda kept reading, I just thought of the same thing
Could you build two+ banks of capacitors that all get charged but each shot only uses one bank, then next shot uses another bank etc, when all the while, the previous capacitor banks are being charged?
I realize this is 3 years late, but look at what this person did! Fully auto, one capacitor blank. Obviously it's not that powerful, but it works! http://www.youtube.com/watch?v=eHv33mH6Nq0
you would have to have different sets of capacitor banks .
for every shot without wait would take that many capacitor banks
moshee Ekzile4 years ago
 you can make it semi-auto easy (this instructable tells you how, actually.)

Making it fully auto is a bit harder, you would need really big capacitors (capacitance, not voltage) and an astable pulse to trigger it.
 it is possible, you would just need, if i am not mistaken, a lot of chargers to make it charge real fast between shots...
gbmaster1372 years ago
how can i integrate a voltmeter to the circuit to see how much charge do the capacitor have while there charging. saw this guy put it in his coilgun http://www.youtube.com/watch?v=shw4lLI45U0&feature=channel&list=UL (somewhat overkill, but still looks nice) and really want to know how to put it
13heinemand2 years ago
My tests with the charger circuits have not indicated that there is a sgnificant increase in voltage output when using 3 volts of battery input as compared with 1.5 volts(for the kodak circuits). The amperage output is also increased more by connecting the batteries all in parallel rather than having any connected in series.

Why is it considered so important to use 3 volt battery packs?
ishmal11032 years ago
The charging circuits have me stumped. I'm pretty sure I have wired right, but when I test them, they don't work. Below is a diagram using your wiring diagram showing how I've been testing them, where am I going wrong?
Charging circut test question.jpg
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