Picture of Disposable camera coilgun
A tutorial explaining how to build your own coilgun from some disposable camera's flash circuits.

It doesn't require much money (if any), but you need some basic soldering skills and electronics knowledge to finish it successfully...

If you have any questions don't hesitate to ask me!
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Step 1: Getting the parts

Picture of Getting the parts
What do you need

- About 5 disposable cameras (used) with flash circuit (you can probably get them for free at your local photo-store if you ask nice)

- A soldering iron

- Some wire

- A plastic ballpoint-pen, ink tube removed so you only keep the hard outer plastic tube

- A light-switch

- Electrical insulation tape

- Plenty of enameled magnet wire (ca. 0,5mm diameter)

- Some soldering skills and some electronic knowledge

Step 2: Disassembling the cameras and getting the right parts

- First of all, disassemble your cameras and carefully remove the flash circuits.

- Look for the big capacitor on every circuit board (a cilindrical thing) and touch both connections with a screwdriver. BE CAREFUL! This will probably give a great spark, since the capacitors may still be charged.

- Choose the flash-charger-circuit board you want to use. Mark the location and the polarity of the capacitor on the board, so you know how to connect the string which will be explained in step 5 later. The (-) side is the one with the vertical stripe printed on the cap above it.

- Identify the charging-button and triggering-switch on the circuit board which were originally used to load and trigger the flash, and solder the wires connected to them together, so the switches are both closed.

- Desolder the big capacitors from every circuit board, and throw away the boards you don't need - so not the one you chose earlier.

Step 3: Preparing for the real stuff

- Connect the capacitors in parallel, that is, connect the (+) and (-) sides to the (+) and (-) sides of the other caps. This is performed easily by using a universal circuitboard.

- Connect the string of caps to the connections on your flash-charger circuit board you marked earlier.
Akshay kapil3 months ago

camera flash circuit uses 2*1.5 volts DC batteries.But I'm trying to make a coil gun of 30 volts dc supply.....can we use the same circuit?? or can we make any intention is to power up the coil gun

Disposable cameras are not really so much available where I live so is there any alternative to a disposable camera circuit? or maybe u can give me some other circuit schematic i can use as a charging mechanism? Thanks

yes if you can find a nerf firefly gun the one that comes with glow in the dark darts and when you shoot it it flashes a light to make the darts glow the circuit is pretty similar.

for some reason when ever i connect my copper coil to the ends of the flash tubes it shorts out my circuit, any idea's why?
using enamelled copper with a 1mm diameter.

it is most likely that your circuit has a problem somewhere on it. Be careful when you are removing the old bulb and make sure to remove it and/or getting the circuit out of the camera. Also make sure that all three of the flash bulb wires are still connected connect the third wire which should be on the bulb itself not the ends to the negative wire. If you don't know which is the negative and which is positive then remove the capacitors and press the charge button on the circuit while you have a volt meter attached to where the coil would go and you will get a reading.

jdorne2 years ago
Tell me, is there any way I could use a 2.5V 55F (they are 55F) capacitor in this? I have 2 of these capacitors. I'm just wondering if they could be used for anything related to this project.
jbewley1 jdorne9 months ago

you could use them if you add in a converter circuit that would change the current from those capacitors into higher volts or you could make a different electromagnet that uses less voltage to get the same strength and the camera flash circuit would still work because they are just basic capacitor charging circuits

Nilpmet jdorne1 year ago
Where in the world did you get a 55 farad capacitor!!!!!?????
jdorne Nilpmet1 year ago
Jaycar Electronics in New Zealand. It is only 2.5V. Its certainly real though, tested it.
I dont think that useing them would be possible for this project as the ones in disposable cameras are 250v~400v.
why don't you build a boost converter? it is more efficient than a camera charging circuit. It just requires some basic knowledge of electronics. really effective too. it charged my12000 MFD capacitor to 63 volts in just 20 seconds. yeah it is 12000 micro farads. works better than a 120 to 480 micro farad cap (single 120 or 4*120 in parallel) charged to 400 volts. you can also build a simple power cutoff system so that you need not disconnect the battery from the circuit. you can control this entire system using just two 555 timers. One for the charger and one for the trigger. it will be better if you replace the relay with a solid state switch like an SCR, triac or a thyristor. mine is capable of switching 800 volts , 260 amps of current. There is also no danger of any welding of contacts. It also reduces the power loss by 30 to 40 percent
why didn't you just say 1.2 millifarad capacitor
I will try it,just give me the circuit schematic.
Hi padmanabhapsimha,

What SCR part number did you use?
my prototype used a TYN616
i used a 'NTE5519' . You can use any SCR or triac with a surge current rating of 600 amps. you can usually overshoot this rating if your cap discharge time is lower than 16 milliseconds
Vorige jaar kwam ik deze instructable tegen en ik besloot om ook een coilgun te maken van wegwerpcamera's. Het was echt tof om het te maken en ik kreeg een 10 voor mijn PWS hierdoor! Mijn versie verschilt wel erg veel van jou, de mijne werkt namelijk gwn op batterijen van de flitscircuit en de spoel heeft 1000 windingen. Als je benieuwd bent, kun je een kijkje nemen:

Ik wou jou bedanken dat je me op dat moment had geïnspireerd! :)
question? is it muzzle loaded, is it a chamber load of sorts?
I'm going to make this some day when I can get enough disposable cameras.
I don't get it, how does it charge?
Inside the camera, when you hold down the button for flash, it charges the capacitor. Snce tou added a few more it might take longer to charge but it charges them all at once. Then when you press the take-picture button it discharges the capacitors to the flash. Little does it know the flash has been replaced with a coil.
nice idea, i assume you could load it before charging, just incase something were to go wrong and it fired whilst you were pushing the projectile in. i guess you ought to test which direction the projectile comes out in before you finally assemble it..
jason10kv2 years ago
It's working!!!!!!!!!!!
I smashed up a window glass by it!!!!!!!
superb performance!!!!! I am just impressed.
PSYCHOMADD2 years ago
Where can i buy some soldering skills and electronic knowlege.
When you say attach them in parallel,(I'm not very good with electronics)does that mean attach the (-) sign to the (-) sign on the other capacitor? Thanks
If you need high current, you would wire them in parallel, positive to positive.
If you need high voltage, you will need to wire them in series, positve to negative
AlfonsVH (author)  electronicfreak228 years ago
That's correct!
alvin98615 years ago
I'm using an old paintball gun for kicking the round stock to the coil. I took out the guns barrel and made a new barrel with my coil on it . I use an auto ignition coil for my power source w/out caps. It does very well w/out the caps and can fire rapidly w/out constant charging.
what do you use to power the ignition coil?
jbussé3 years ago
+32 number that ought to be BELGIUM !! hallo mede bewoner van het regeringsloze land :D
AlfonsVH (author)  jbussé3 years ago
Aangename kennismaking lotgenoot!
Hoe lang nog, gewaardeerde zuiderburen?
AlfonsVH (author)  diy_bloke3 years ago
Ik heb er geen idee meer van...
Di Rupo ook niet meer :-)
lakevista54 years ago
I made a Coil gun using 15 capacitors with a total 300v and 1880uF with a single stage coil.  My coil is 39mm long  and 5 layers thick, using 24gauge magnetic wire.  the problem i am having with the gun is that it shoots backwards.  at 100v it shoots forward, at 125v to 175v it does not shoot at all and 200v to 300v it shoots backwards. 

what should i do... should i decrease the number of capacitors, increase the voltage or change the coil.  if the coil is the problem what size would you recommend?
Sorry if this is a bit late, but.... from comments on a similar instructable I'm betting that what's happening is that your coil is energized long enough for the projectile to get sucked back through again after launching the right way. Maybe move the projectile farther back from the coil? That way it's got longer to accelerate forwards before the coil's pulling it back.
I suppose you may be able to use some kind of Micro-controller chip to only allow electricity through the circuit for a short time (milliseconds, for the ammunition to go from the loading end of the barrel to the midway point) and then it could let the projectile shoot out the firing end without any sort of backwards dragging force from the magnet?

I am only a novice (if that) to electronics so I have only little knowledge on how well this would work.
I would be careful when introducing semiconductors into the coil stage of the gun, and would be *extra* careful when hooking it in any way to a microcontroller. The difficulty is two fold:
problem number 1 is you have the capacitor discharging into the coil, and according to ohm's law, current is directly proportional to voltage for a given resistance. The instantaneous current from that 330V cap can easily be hundreds of amps, and I have yet to see a *common* transistor survive that rush of power when you flip that discharge switch (in my experiences they'll likely fail in the most explosive way possible). Hook up a transistor you don't mind killing in place of the coil and you'll see what I mean.

Problem 2 is the coil is a giant inductor which you're passing very large current and pretty high voltages through. When that field collapses it'll induce *more* current, which has to be anticipated and dealt with, It's the same reason you can't hook a motor directly to an arduino.

I'm not an expert, so some of the details could be off, but in my personal experience, I haven't found a way to use commonly available parts to control a coilgun due to the incredible amount of power they'd be subjected to.
I do agree these all seem like major problems.

To resolve problem one I would, with my minimal knowledge, try to add a high operating voltage relay switch into the charging/discharge circuit, though if this works it would be hard to implement into an instructables due to the many different commercial circuit designs for flash op boards from cameras.

In regard to No. 2 I have very little knowledge of inductors but could you add another inductor which will take away the problem into a suitable circuit.

These are my novice ideas so can people please correct me and suggest suitable solutions.
You could also make a bigger(longer) coil or use thicker wire. This would allow the electricity to pass quicker, maximizing the use of your cap bank, and not overkilling the coil
what kind of power were you getting? cuz i want to make a rail gun on a simmilar bank (actually about twice that....), and an interested in your results...
cherwa5 years ago
do you have to put the capacitors in order from biggest to smallest? or can they be the same size?
leven cherwa4 years ago
If you need to ask that, you should not try this.. the 300 volts cap would have no trouble killing you.. so read up a bit on basic electronics and you will now the answer, and how not to kill yourself.
I tazed my self atleast 300 times with just one capacitor of 330v and hey i'm still here It just hurts like hell for about 2 mins
i care to disagree. 300 volts means crap if the amperage is super low.... like a flash camera's cap is. besides, volts don't kill, amps do.
no, it dosn't matter in parralell the capaciter volts/uf are added together
No, in parallel the capacitance of the capacitors are added, not the voltage.
In series, the capacitors voltages are added together, and the capacitance is taken away from each other.
Do the capacitors have to have the same rating if I wire them in parallel? I have 2 80uf, and 4 160uf but they have different voltage ratings. Can I use all of them together?
Articas3 years ago
do i have to leave the flash bulb in the camera circut
no you have to take it out
R.A.T.M3 years ago
how do i know wich way it fires
Aim it at your face and fire it. You'll soon find out.
usb key3 years ago
A diagram would have been nice
R.A.T.M3 years ago
pleas help if i have the coil coring the hole pen but 1 1/2 inch n the front
fsilva-13 years ago
The battery is not charging the circuit. I have tried everything but it is useless.
bendog384 years ago
 would a .177 caliber pointed airgun pellet work as ammunition

 what about a small plastic airsoft bb           and what is the fps on this thing

it would work in a rail gun (the lead pellet), however. but as they said, it has to be magnetizable (for those who don't understand 'ferromagnetic')
then how do I make a rail gun? seriously, i want to know, i have a science fair at my high school coming soon.
i would advise you not to build a railgun with just basic components for a science fair competition. a coil gun will produce more impressive results and it won't be damaged by wear and tear if you construct it properly
sorry for the late reply. a rail gun, in it's most basic form, is just two rails that you pass lots of current through. i made one once from tin foil and a nail. it was a really childish effort, but the nine volt battery was enough to burn holes in the foil, which was neat.

there are several sources for rail guns on the net, do some searching. and above all, be carefull. the bigger the gun you intend to make, the more likely you'll kill your self with electricity.
Neither would work because plastic is nonferrous and airgun pellets are made out of lead, which is also nonferrous. As for fps, I don't have a clue. 
fps would really matter on how much juice your giving it, right? so theortically, no two shots would ever be the same without some kind of capacitor measuring thingy.......
Pretty much. But I'm not sure how much of a difference there would be.
it has to be metal
If it's a plastic pellet, unlikely. Coilguns shoot projectiles with a sudden pulse of electromagnetism, ergo any projectile must be ferromagnetic i.e. made of iron or another material attracted to a magnet.
Ma77h3w4 years ago
I created one using just the circuit from 1 disposable camera.. and used a push switch to activate it. This welded shut and was rated at 250V ac at 5A I've got a relay to do it now rated at 28V dc / 277V ac at 12A. Will this work? What sort of current goes through a coil like that? My coil has almost no resistance
you do not need 28 v dc to activate the relay. usually relays need 9 to 12 volts to activate them. your relay's ratings is the maximum voltage and current it can switch.
zack247 Ma77h3w4 years ago
you will need close to 28v to activate it, try finding a car relay at your auto wreckers, they can be activated by 9v and are simple to use.
one is used in this instructable:

loko at picture 2 of step 4 to see how it is wired up. on the bottom of some relays there are markings, the two pins marked with a swirly sort of line is where you put the 9v, and NO and COM are your "switch" leads
zack247 zack2474 years ago
COM can also be labeled as just C, too.
Ma77h3w zack2473 years ago
Ah I know how to use a relay. and it's a 9 v activating voltage, those were just the ratings I mentioned before. I'm just wondering whether it would fuse. Cause I'm sure more than 12 A goes through it when it's connected to a coil like this
zack247 Ma77h3w3 years ago
relays dont generally fuse, it should be alright.
im not sure if relays have the max current that you can put through them labeled on them, some do, if you want to be extra sure then check your relay and see if it says anytihng.
Ma77h3w zack2473 years ago
Yeh it says 28V dc / 277V ac at 12A
Hard to know the current through such a short coil like that. I imagine it'll cope with more than 277V ac at 12A if it's just a pulse. The ratings on it are for a continuous ac or dc voltage, so I guess I'll find out when I finally try!
i have similar problems; if some one who knows about relays could help.
Ma77h3w Ma77h3w4 years ago
Also I have loads of 0.1uF Capacitors:-
Class X2 Metalised Polypropylene Capacitors
Voltage rating - 275Vac
Tolerance +/- 10%
All carry international electrical safety approvals.
Typically used as suppression components.

Would these be suitable for a coil gun? They're some of the few high voltage capacitors I have. I imagine I wouldn't want to increase the voltage above that of the standard camera flash charge circuit, but would I instead use a thicker coil wire for more current?
Hav0c3 years ago
I have got 3 camera charging circuits and 12, 330v caps is it possible to connect the charging circuits in series to get 990v and connect them to 4 parallel rows of 3 caps in series
AlfonsVH (author)  Hav0c3 years ago
I think so, but I'm not sure...
More power!4 years ago
Won't a switch weld together? (Push button)
AlfonsVH (author)  More power!4 years ago
Possibly, but not in my experience.

You could consider wiring a SCR or something to take care of the switching.
Ok, I'm not going to be working with that much electricity anyway, so I think that I'll just chance it

P.S. I only have access to two kodaks :( That's why I won't be using much electricity.
which is more important in determining the energy produced by the coil gun, the number of microfarads a capacitor has or the number of volts a capacitor can hold?
AlfonsVH (author)  cardboarddude4 years ago
The capacitance (farads) is the important factor.

The voltage rating does not tell anything about the amount of "volts a capacitor can hold" but it is the maximum voltage the cap can withstand.

If charged with a higher voltage it will hold more energy, so it is still best to use a cap with a high enough voltage (a little bit higher than the voltage of the source you use to charge it)
how can i increase my coil guns power? right now it has a capacitor bank with about 3000 v and 5300 uF, the coil is 1 inch long and 1 inch thick and it shoots an inch nail only about 10 feet.
cvandyck4 years ago
Is there any reason that you cannot use a 9 volt battery, and if so what are the advantages of using it, over a single 1.5 volt?
AlfonsVH (author)  cvandyck4 years ago
Using a battery (1,5 or 9V) would be possible, but it would take longer to completely charge the capacitors.
k.. so what battery or power source do you recommend?
AlfonsVH (author)  cvandyck4 years ago
I used a 9V 2Amp source, which is what I would recommend.

A normal 9V battery or some kind of heavy-duty battery might give similarly good results, but I suggest you use whatever you have lying around the house :-)
big-jamie4 years ago
(removed by author or community request)
AlfonsVH (author)  big-jamie4 years ago
Not sure what you're asking here... could you reformulate the question?
AlfonsVH (author) 6 years ago
Various people requested schematics et cetera. I uploaded two files describing the building process somewhat more detailed on my server: Basic Manual and Addendum
AlfonsVH (author)  AlfonsVH4 years ago
Files have been moved to another server and can be found here and here.
frixx5 years ago
you have to connect the caps in serial to increase the voltage
Vator frixx5 years ago
And in parallel to increase the µF?
 You mean capacitance.
.... isn't that what he said? (seriously, i don't know the diference between capacitance and farads)
No, (micro)farads are the units. That's like if you were to cut a strip off of the end of a piece of paper and saying that you have "decreased its centimetres", when the correct statement would be that you have "decreased its length".
would saying 'the amount of uf' be proper? and thanks for exsplaingin that...
hey im wondering if its better to use 330v caps or if i can use 100v caps in parallel? i guessing it would charge faster too. also is it better to have a longer coil or have a thicker coil? thanks
The charger will put out around 300v. Capacitors will blow up if their voltage is exceeded too much. If you hook up capacitors in series, the voltage increases when the capacity decreases. In parallel, capacity will add up while voltage stays the same. So 100v caps in series would be okay, but you have to be careful because u really should use bleeding resistors. With 330v capacitors, feel free to hook them up in parallel. (on a side note, if capacitors all discharge and one discharges early, the capacitors can discharge through the early discharged capacitor and blow it up.....)
on the last statement, that would be if their in series, yes? to ryan, first where do you find 100v caps? i have at least 30 flash camera caps (and plan to get more) and all of them are 330v (perhaps you are seeing 100mf (micro farads) which is a measure of amps.) i've been told by several sources that for this kind of application, one should wire one's caps in parallel

don't know about coil length....
100v caps in series


330v caps in parralel

330v caps are usually around 80-120 uF

You don't have to use more than 1 330v cap if you don't want to.

And 30 caps, thats more than enough
ah... okay, that makes sence.
The website doesnt work!!!
can someone explain to me why the trigger switch's contacts don't weld togheter? i mean, the coil IS basically a short between the capacitors right?
(removed by author or community request)
that doesn't exsplain why the trigger switch's contacts don't weld together...... and from what i've read, that actually happens alot...
(removed by author or community request)
so basically all that energy goes into making an electromagnetic field and instead of causing some sparks?
sorry if this is a stupid question but when you make the coil do you wrap it one way, stop at the end, then wrap it back the other way so that you have 5 or so layers that go right and 5 or so that go left?

actually no, you have to wrap the wires the same way every time. otherwise the electromagnetic fields would cross with each other and cancel each other out.
The charger will put out around 300v. Capacitors will blow up if their voltage is exceeded too much. If you hook up capacitors in series, the voltage increases when the capacity decreases. In parallel, capacity will add up while voltage stays the same. So 100v caps in series would be okay, but you have to be careful because u really should use bleeding resistors. With 330v capacitors, feel free to hook them up in parallel. (on a side note, if capacitors all discharge and one discharges early, the capacitors can discharge through the early discharged capacitor and blow it up.....)
Whoops. It glitched.

i thought electromagnets only had 1 "polarity," so it would attract iron no matter how i wind the coil.
.... well, no matter the polarity, it will still attract the iron....... simple test is to take a magnet and put it on metal, first on side, then the next. it will still attach.

scientists actually have yet to make a magnet with only one pole, so that would be pretty amazeing if you did it with a simple electromagnet.....

like it was said befor tho, wind in the same dirrection. it shouldn't matter which way though.
berky934 years ago
I have two related questions:

My flash bulb has 3 wires coming from it. A white wire connects to one end of the bulb, a red wire to the other end, and an orange wire connects to a copper sheet that wraps around the back of the focusing panel behind the bulb. Which connections do I solder to the coil/firing switch array, and where does the switch go (as in, does the switch go between the coil and the red wire, or in between the coil and the white wire, etc)

^the circuit was taken from a generic brand disposable camera. I would use a kodak brand but I couldnt fit it into my casing. I only have 3 capacitors (all the same capacity as the camera's original capacitor) so there isnt too much extra energy to worry about.
freerunnin14 years ago
does anyone know the best type of wire for a coil gun coil?
erty3114 years ago
Will a 1000 µF 35v capacitor work for this project? or do I need a higher voltage capacitor?
bendog384 years ago
Does anyone know the range???
max1zzz4 years ago
 what would happen if i used 2200uf pc motherboard caps
leven max1zzz4 years ago
They would go POFF, and the blue smoke would have been released.
they are rated someting like 6 volts, while the flash charges up to 300 or something like that. 
junits156 years ago
here u can buy camera flashes! real cheap!
dude, you can getem for free if you ask for used ones
i might but do u think they will give cameras to a 14year old?
I have gotten 35 in three days and I am 14 but I have had people think I am 10 or 11. say you need them for a science project involving the flash circuit
ok, i heard that walmart gives the most so ill try that there
I tried there but they said they recycle them so i'm going to try walgreens
if you live near costco, they give you as many as you can take.
really? thats awsome! but i don't live near near costco :( only a bjs i used to live near a costco
Oh, that kind of stinks... They had a kind of big trash can FILLED with disposable cameras! I one time even found a perfectly good regular camera in with the others! Seriously, you could just fill a cart with them! Good ol' costco...
i live 5 mins distance..walking from a try 14..but iv had alot of comments asking if i was 17
Be careful with the circuits before they're discharged... Just got zapped and it burned me... 2nd degree on one lead and 1st on the other, and it hurts like CRAP!!!
Yes, I tried to discharge the capacitor with a pair of pliers, however, there was a bit of insulation missing on the handle.....300 volts went through my arm and knocked me out of my seat.
i never got burned by it but i swore a heck of a lot in my basement. when prototyping i did not insulate the trigger and the push button was not supported because of no case i touched the leads accidentally and all day i was shaking!!
but no burn at all? why did u get burns? i used 7 120uf caps
that is where I got most of mine 32 in 2 visits
how about CVS theres one a few blocks away from my apartment, do they give away cameras
It depends on if the person working there is nice or not but they should.
I went to CVS and they didnt. they had some policy against it. They new somehow wat i wanted it for
my little bro is 12 and he got twenty cameras from wallmart. he was on his own without anyone else. so ya they would give cameras to a 14 year old.
well it really depend on who is behind the counter.
hey, i'm 11
did they give them to u? what store did u go to?
how many did u get?
15 for free
what d u ask? (what did u say to whomever)
DYLEGO junits156 years ago
oh my gosh! dude, walk into walgreens and ask the person at the photo counter if they have any used disposable cameras. you're wasting comments here!
junits15 DYLEGO6 years ago
wasting comments? oh please calm down
DYLEGO junits156 years ago
seriously, ever learn to know a joke when you see one?
imrobot DYLEGO6 years ago
i eat comments
DYLEGO imrobot6 years ago
ohhhhhhhh-kay... that's not weird at all...
imrobot DYLEGO6 years ago
guydie5 imrobot5 years ago
imrobot guydie55 years ago
reaper baku4 years ago
how big is the coilgun
dumdog9277 years ago
can you email me what the trigger switch looks like at or send a comment repley
AlfonsVH (author)  dumdog9277 years ago
The trigger switch is the red button as shown in the pictures. It's just a switch which is switched on when it's pushed, and off when released.
i mean the trigger on the NEW disposible cameras cause i cant find any old disposible cameras with obvious trigers
AlfonsVH (author)  dumdog9277 years ago
That depends on the brand of camera you're using. I'll send a PDF-document with a picture of a KODAK-board to your email address. That may be what you're looking for.
AlfonsVH (author)  AlfonsVH7 years ago
@dumdog927: Your email address doesn't seem to work. I uploaded a PDF-file to ; you'll find the pictures in that document.
what you need to do is connect the two pices of metal sticking out and that will cause it to flash/fire!!!
What do you mean by connecting them? Solder them, solder another wire to them, etc? BTW, is down, and the closest thing that is still up is some music site.
well those 2 wires that stick out just need to touch or have the current bridge across them... so solder a switch across them or 2 longer wires.. just make sure it isnt always bridged.
i think your kodak camera is either and old type or a different type from the one i have it has a push button for the charger
sry my email is but i took apart a kodak and its circuit bourd looks different its like green and where can you buy a universal circuit bourds? thanks for the help so far (:
kevinlei3245 years ago
I have a holder for 4 AA batteries.. I know putting them in a series increases the voltage, so is it still safe to use that as a power source for the camera circuit?
only for a couple of shots, probably. then the transformers on the board will blow and you'll be left with a nasty smell and a busted coilgun
derbert4 years ago
DON'T throw away the other boards the other boards, you can use them for tasers, even without the huge caps
How do you attach the capacitors to the breadboard?
Do you attach the flash circuits to the circuit board out of the camera? If so, I have a kodak board and I don't know where I need to solder them to. thanks
AlfonsVH (author)  flash circuit 27 years ago
This link is broken, can anybody help?
Geemo54 years ago
wtf dont stress disposable cameras are so easy to get i took a public bus to 2 photo developing stores, asked nicely and ended up with 13 disposable cameras, im only 14. i didnt spend a cent.
Is it the same camera circuit just with extra capacitors?
well you can make a very simple one just add more caps to the camara and take out the light put there a coil
on the kodak curciut boards where is the switch to fire it ?
my mom works at wens so she can get them whenever she wants yay  itold her i was making a cool thingamabob because she doesnt like me with high voltage hehehhe
Arduino Guy5 years ago
THIS IS AWESOME!!!!!! i made it and i shot a nail into a fiber board 0.5 cm thick and the nail went through!! but winding the coil is awful. i did only 6 layers of coil that time...
Mudbud5 years ago
pearce6065 years ago
i agree with pie. more pics would be cool. my coil gun doesnt seem to work. the battery just gets hot and the capacitors charge but nothing happens. any help?
if it gets hot then it is sorting out so look for any wires that could be the problum
What capacitors are you using?
did you wind the wire in more than one direction? because if so, you will need to re-wind it..... only wind in one direction or the other!
The battery gets hot? I don't think that's supposed to happen.
check for short circuits. after many charges, the battery should be warm, but not hot. only use AAs.
Give some details... Anything could be possible. Anyways, here's a checklist. NOTE: DO NOT USE ANYTHING BUT 1.5V IN THE CHARGING CIRCUIT. ANY HIGHER, AND THE CIRCUIT WILL FRY. That's another possibility, by the way. -Is the charging circuit working? (connect an AA battery to it, no higher voltage) -Is the coil working? (connect high voltage, high current to it) -Is the wiring ok? (check everything manually) -Are any switches welded together? (high voltage causes this, using a relay is much better.) hope this helps!
joemonkey5 years ago
ok, i'm making one of these using the gun from mission paint ball,and i have soldered everything down, but once i put the batteries in a small black three pronged resistor( i think) caught on fire. now the board is fried. what did i do wrong? i hooked it up to 4 AA Batteries, if that helps.
patlynz5 years ago
which one is the light switch?
patlynz5 years ago
which one is the light switch?
Ganonman5 years ago
how powerful would this be?
amando965 years ago
can i use the smallest electronic shocker to charge the capacitors? the complete camera circuit is too large to fit inside my gun case :-s

help, thanks :)
amando965 years ago
another question. can i use diferent voltage and capacitance capacitors on one bank? or do they have to be the same?
eneergcam5 years ago
coil guns are cooler if they look like guns
especially if they look like star wars blasters
I'm building one using a gutted out Steyr AUG airsoft gun. =)
JimJong5 years ago
could I use 26 or 30 gauge magnet wire for the coil cuz its all i got? if i can how big should it be?
what is the minimum amperage rating needed for the fire switch and what will happen if u use something lower, like a 20a light switch?
alienwear5 years ago
Anyone who can't find camaras my advice is to ask everywhere. I found that most places wont give you any, however I found one shop with a huge bag of them that I got for free. Thats over 100 camaras :D . Now I need some more solder.....
i am noticing some contradiction between diffirent coil gun ibles. some say to use a charger bank, while others just use one charger and it seems to work fine. wat are the advantages and disadvantages to useing a bank as opposed to a single charger?
More chargers = faster charge time but larger size.
markubiak5 years ago
I'm using coated 12 gauge copper wire. Will this work?
Of course. However, because 12 gauge is much thicker than the commonly used 22 gauge, wind less layers. (for example, one inch long coil, 4 layers thick). Hope this helps!
Badetise5 years ago
hey jst wondering, if i use a disposable camera board thing w/o the capacitor, and hav the would-be charging voltage giong into two probe-things, could i use it as a power supply for a clod heat soldering iron? i wanna make 1 really bad but i dnt hav old computer to take the power supply out of and the closest computer repair shop is FAR away.. please help..
Sorry, no. The terminals that the capacitor is connected to is high voltage, but with nearly no current. So, electrical appliances of any kind are out of the question.
guydie55 years ago
yo i was just wondering if i could solder alot of 250V film caps that i bought at radioshack together (bear with some of the grammer my keyboards punct keys and others are broken)
OK ill try this tomorrow 11:00 now got to go to bed ill have to buy disposable camera I guess and ware rubber gloves and some switches do I need an led light buy one I mean
pleas learn english... if you dont, nobody can understand your questiony, so nobody can answer it...
Ummm... Please learn English... If you don't, nobody can understand your criticism, so nobody can improve according to it.
Kaiven Tommyhzy5 years ago
LOL! "questiony" :P Nice one Tommy! Some people in this world do care about grammar and spelling...
Has anyone really been far even as decided to use even go want to do look more like?
Kaiven5 years ago
How long does it take one circuit board to charge 4 capacitors? My capacitors never charged, and so nothing happened. I think i need to practice soldering....
I put everything together and i got the capacitor bank to charge and i got a huge spark when i discharged it with a screw driver. But when i hook it up to the coil, the nail/screw/ammo doesn't move at all.... How did you get this to work Email me about it at
It's best if you put the ammo in the back half or behind the coil. This is because the coil needs to become magnetic and draw the ammo forward to make it go fast.
make sure there are not too much or not enough turns in the coil. also, try playing with different projectiles and placing them in different positions around the coil. i get good results if i put it (a small screw) in the back half of the coil. make sure you do not put your projectile in the middle of the coil, because that will just hold it there and not do anything cool.
aplauche5 years ago
could you give me some specs for the average capacitor found in a camera? i have a bunch of good condition capacitors lying around from other projects, but i would like to know the power that you generally use. also wouldnt using one huge capacitor rather than four medium ones decrease the charge time?
The average camera capacitor is 330v and 80 to 160 uf.
shinizaki5 years ago
I dismantle Fujifilm Cometa camera and confused by charging sequences. Do you know how fujifilm charging sequences ? Then with luck, sometimes its charge successfully (but still can't figured the charging sequences), but when I connect the coil with the circuit, there are spark in the switch. Is it because the switch doesn't strong enough ?
shaunak6 years ago
What values are those capacitors? Itl be far cheaper to buy capacitors than cameras!
check they usually have photo flash capacitors and disposable camera boards for very cheap
I also got some GIGANTIC capacitors. It says they have 250 volts or something. I think it will take a long time to charge but the blast will be strong. U can also find capacitors EVERYWHERE(radios, computers,EVERYWHERE):)
Yes, but camera capacitors have 330v...
ya there great I bout 2 of the small surprise boxes an wow way over 2000 parts
Gjdj3 shaunak6 years ago
Yeah but... just go to your local (insert Walgreens/Walmart/PhotoDeveloper here) and ask for some old disposable flash cameras. I walked away with two bags full (a lot of projects use these). Totally FREE!
Magre1441 Gjdj36 years ago
Alot of places i went to wouldn't gimme any because they recycle them, mostly chain stores. But most of the little local shops let me have some.
In one visit to walmart I got 24 cameras mostly Kodak and 8 the day before from the same walmart all for free. :D
Mattrox Gjdj36 years ago
Yeah i got bout twenty from my local kodak shop for free and with a bonus most of them had aa or aaa batteries and had alot more than half of their power in them
i got 21 free, they where broken on the outside, but all the chips were mint...
DYLEGO shaunak6 years ago
get free ones at the store... you need the high voltage!
Tobita shaunak6 years ago
you need the camera becuase it has the transformer that changes the low voltage to a high voltage while possibly lowering ampherage.
macwhiz shaunak6 years ago
you can get used disposables from your local camera developer cheap or even free
330v 120 uf
frixx5 years ago
I want to know will it work with two 350w capacitators on paralel ? you can send an email or just reply here thanks!
Yes it will.
GEEK16 years ago
I have a question for AlfonsVH I don't have a solder but can I just make the contacts touch and tape it together?
No, there's way too many connections to just tape them together, and most of the leads will be way too small Your much better off going to a local electronic shop and buying a 10 dollar iron.
Thanks for the help !!! :) By the way can anyone invent or tell me a gun that can be used in my office and is disguised as a pen, it would be very good if the gun can shoot very far
get a pen you can fit 6mm (standard size) BB pellets into. load it up and use as a blowgun, that's the simplest way or you can add on a crazy aerosol exploding bomb firing shooting omnipotence yet omnipotent killing bit. Damn B.P.E. lessons ZZZZ
Pie Ninja GEEK16 years ago
Get a pen, remove both ends, hold an elastic band at one end and pull the ink back into it like you would a slingshot. I have broken CDs, put holes through coke cans and made people cry using this.
Essentially a crossbow. I have a friend who did that and fires PENCILS out of it. Sharpened PENCILS. Those can really hurt.
interesting friends...
junits15 GEEK16 years ago
you could solder with a lighter, then all you'd need would be some solder wire for like $2 at radioshack
frixx5 years ago
my email is
mman15065 years ago
do capacitor have postive and negatives
some do....i dont think disk caps do though
calpul5 years ago
also put i video on showing us how good the coil gun is plz.
calpul5 years ago
it works i went to my local photo shop and sadi i was doing a school prodject. i said i will need 4 cameras. and she gave them to me for free. well she gave me 6. she said have an extra 2. result. DO NOT BUY THE CAMERAS NEW JUST DO WHAT I DID, GET THEM FREE.
Baddul35 years ago
How do u attach all of the capacitors to the leads of the original capacitor?
anubreed6 years ago
When you say magnet wire do u mean copper wire. or is it that kind of wire thats wraped around a square block in side a radio or some thing and if so can i just unwind it from that and use it for this.
Copper wire would just short. Magnet wire has enamel on it so you can wrap it without it shorting itself. Yes, it is the kind of wire that's wrapped around a square block inside a radio.
yea but the one inside a radio is really thin, and has better use for radios... xD
cyrozap cyrozap6 years ago
"Bare copper wire would short" is what I meant to say.
ryan3606 years ago
i got 23 cameras from cvs and im 14.......made a huge rail gun really sick you can do anything if you learn/work on/with electrical stuff just keep takeing stuff apart to see how it works youll get really good at electronics like i said im 14 and a member on a few tech forms
junits156 years ago
now, i have a burning question about this. does the coil go in the front or the back of the barrel, or does it go in the middle? it seems to me that a short barrel ith the coil in the front would be most efficiant. could somebody please help me! i want to make a larger scal one but i cant figure this out.
The middle with a long-ish barrel most likely. Added barrel length gives added accuracy, and the coil needs to pull the projectile towards it, but cut off the electricity before the projectile is inside the core of the wire.
is it hard to get the timing right?
recon5066 years ago
is it possible to wire all the caps in series? i'm asking because i'm experimenting with wiring all the charging circuits in series to charge a 700v cap i have lying around. if anyone has done this, or knows what im talking about, please reply because im kinda stuck right now.
DYLEGO recon5066 years ago
wiring in series gives you less... wiring in parallel gives you more
d306 years ago
hey would anyone b willing to sell a coil gun for like 50 or 100 bucks?
DYLEGO d306 years ago
yup me!
DYLEGO DYLEGO6 years ago
ill sell for 40!
DYLEGO DYLEGO6 years ago
i have excellent soldering skills and can send it within a week or two!
DYLEGO DYLEGO6 years ago
ill sell with ammo for 50! i can put it buy it now on ebay and tell you, then you go buy it!
Mandrax6 years ago
...Desolder the wires connected to the flash tube (and to the reflector attached to it) and mark the places where the two main wires were...

I'm just wondering where you soldered the wire which was attached to the reflector? does that actually do anything? or?
Pie Ninja6 years ago
Some more detailed images would be nice
Kaiven6 years ago
:( How do I wrap the coils on the pen? How many layers, how long is the wire?
Kaiven Kaiven6 years ago
Woops! I see it now, but is it okay if my wiring isn't straight?
gmangrey6 years ago
Questions, what is the usual Volt / uf for disposable cameras, how far does this thing go and would it be possible for you to draw out a circut diagram for me?
1arrow246 years ago
Exactly how powerful is this coilgun?i.e. how far does it shoot etc...???
JellyWoo6 years ago
wat is a coilgun?
A coil gun is an electromagnetic coil which is activated by a rapid discharge from a high voltage capacitor bank (basically a number of capacitors linked together to act as one giant capacitor) in doing so creating a large burst of power to surge though the coil in a mere fraction of a second creating a powerful (but short lived) magnetic field at its center which draws in the metallic projectile at high speed and if timed right the discharge will end just before or as the projectile reaches the center of this field thus making the field disappear before it can pull the projectile back once it has passed thus allowing it to maintain the speed it gained in being pulled in.
oh, okay.
Andruha11236 years ago
walmart only gave me 2 cameras, they said that they have to recycle them. i'll try another walmart
ya, they sell em back to the manufacture so they can reuse them
It is actually illegal for them to give you the cameras now because its possible for people to make bombs out of them apparently... honestly any one with half a brain 10 bucks and a few anger issues can make a bomb so I dont see the point.
davidemil556 years ago
ok i got a queastion, could u maybe draw the curirct out something because kinda hard to follow from the pictures and how much fps do u think that is?
ya seriously i can't get my hands on disposible cameras so if anyone knows the value of the capacitors it'd be great! thanks
ya, wopuld have been great if you listed some values for the caps. Jeez, I've got half a parts house lying around my room, but no camera's.
mine were 330 volt and 80uf
Well I just went to the nearest wallgreens and told them it was for a school project and they gave me seven used disposable cameras for free.
lol when i ask 4 used disposable cameras they told me that they got crushed up and put in the bin . . . maybe they don't want people 2 make tasers out of them.
ppft, they send them back to the manufacture and reuse what they can. Worked at a wal-mart photo center for a summer.
Sprescav6 years ago
I wonder what would happen if I put a fence electrifier instead the capacitors and disposable camera circuits... that thing works at about 150.000v.. could be far better than the 500v power from capacitors...
how far does it go?
aodshocky6 years ago
I have a question on the coil creation. lets say I start on the left and wrap it to the right, when I get to the right hand side do I pull my wire back to the left and restart on the left going right again OR do I go back to the left?
Pbyrd7 years ago
I am making one of these for a school science project and I was wondering if you could use an Altoids tin for the box?
hmm, high voltage capacitors and metal in your hands, not the best idea. nice creativity though. p.s. if there is room you might be able to pull it off by lining the inside of the tin with a non-conductive material.
Radioshack has some project enclosures, but not necessarily Altoid tin shaped. You could just line it with trash bags, but there's still the possibility of leads poking through. If all else fails, put it in and fill the tin with non-conductive epoxy or other non-conductive hardening liquid.
yeah the boxes that the Shack sells are pretty nice for high voltage, i use one to hold the charging circuit for my coil gun.
Same here.
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If you can find it, get some spray-on PlastiDip. It's non-conductive, and you can use it to coat the inside of your tin so that you won't ground out your circuit.
hay can I use np caps (none polorized)
Can i use the capacitors found on computer power supplies?
Yes, all capacitors are they same. Except for the ammount of voltage and the other thing. :/
Mattrox Kydoes6 years ago
The ultra freqeuncy think its got somthin to do with the high pichted noise it makes when charging o by the always short the capicitor before touching the circuit (i learnt this the hard way)
I hate flash capacitors... i took apart a strong one and couldn't feel my hand for 5 minutes...
I know It is flippin sore
i got a new one from a camera, and when i discharged it it shot a jet of sparks and nearly set my room on fire. should i use that for this or a taser?
Its your choice if you thought about you could make it into the design so that press one button and you get a shock other button makes sparks
Aqlor Mattrox6 years ago
I think he wanted to ask if the output was near 200v because thats the big capacitators value found on power supplies. If the output of the circuit is 200V you can, if it is bigger (which i think it is, we are charging 330v capacitators afterall) the capacitators can be damage. Can anyone measure the output of the charger circuit?Currently my coilgun as 8 capacitators (330 v .. 80*4+120*2+160uF =720uF) If i used capacitators found on power supplies I could get much higher capacitance and lower voltage.First post yay
All capacitors are not created equal but for this project i suggest electrolytic caps. (The water tank lookin ones)
is it possible to do this with a battery inside the can? i intend to make a larger one and use a home-made taser as my power source/secondary weapon-thing by making a socket for it on the bottom.
should we hesitate to tell you that we hate you for figuring this out before most of us?
ok; I hate you for not making it so u can use one...
Mattrox6 years ago
What sort of wire can i use? and will it matter if i use capicitors from different cameras?
No it wont but what kind of wire for where? The wire to the coil would have to be at least 14-12 AWG.
thanks i meant the coil anyway. what does awg and where can i get it from?
The coil should be magnet wire prob 16 or 18 AWG. AWG stands for American Wire Gauge, its just a unit of measure not a type of wire.
Relentles$6 years ago
i built this to specs i get the led to light up with four capacitors and i get no ignition!? when i run a nine volt thru it i just smoke out one of the transformers whats wrong??
you leaked the smoke out :) just jk.
vorian6 years ago
`yeah how do you see the little boxes?
vorian6 years ago
Is it possible to do with live cameras? also, what ammunition does it use, and how do you load it?
jongscx7 years ago
Alright, to answer some FAQs that I've seen: 1)If you go anywhere that develops film, you can get disposable cameras for free, if you ask nicely and they're willing to give them to you. social skills are a must. 2) There were 5 camera circuits used in this project. 4 of them were scrapped completely except for the capacitor. The fifth one is used to "load" or charge the capacitors AND to trigger them to release their charge. The COIL IS CONNECTED TO THE FLASH TERMINALS, not to the capacitors directly. The "Trigger" switch is connected to the switch that made the camera take a picture. IT IS NOT CONNECTED TO THE CAPACITORS. Therefore, you do not need a 300V 150A switch for the trigger... 2 paperclips will work too. The "Power Supply Connectors" are connected to the original battery terminals on the circuit board. THEY ARE NOT CONNECTED DIRECTLY TO THE CAPACITORS. The circuit board does the charging, etc. The "Status LED" was just extended from its original location. It lights up when the capacitors are charged (aka, when the flash is ready) 3) the capacitors are all connected in Parallel, meaning all their (+) are connected together and their (-) are connected together. If you plan on adding more capacitors, add more coils to your gun. 4) The coils all point in the same directions. Do not wind in one direction (let's say to the right) stop, then go back to where you began (left). WIND IN ONE DIRECTION, GO BACK TO YOUR STARTING POINT, AND CONTINUE TO WIND IN THE ORIGINAL DIRECTION. 5) just because someone is typing in all capital letters doesn't mean they know what they are talking about. They may think they do, but that may or may not be true. It is usually to add emphasis to something, though, so it means they want you to read it. 6) In Step 2, the green wires labeled "To the battery" are actually going to the LED. The wires connected to the battery are not labeled, but are the red and white wires next to the capacitor that are connected to the little bit of circuit board.
so i wind the wire across and make a coil as it shows in the pic, and then go back with the same peice of wire and make another coil around the first one with the same peice of wire? that leaves a big lump in my coil.
if you really want to, you can make a bunch of overlapping coils, nesting the next layer in the dips of the previous layer, then connect them all in series with wire at the end... Basically, my point is that the electron flow will need to be traveling in the same way, same direction, same direction of spin for the effect to be amplified. If they're not, they will weaken each other, kinda like opposing forces
jwm22 jongscx6 years ago
would you cover each row of coils in electrical tape or would you just lay them on top of each other with out separation
thanks, i'll do that. you have been a great help, cheers
sajada jongscx7 years ago
Thanks for clearing that up guy.
munchman7 years ago
How do you discharge the capacitors. I once (twice, now that i think about it) took apart a disposable camera and well.... ouch.
AlfonsVH (author)  munchman7 years ago
As described in the original instructions: "Look for the big capacitor on every circuit board (a cilindrical thing) and touch both connections with a screwdriver. BE CAREFUL! This will probably give a great spark, since the capacitors may still be charged."
I used an iron rod, and just touched between terminals, and it discharged it with a spark and a bang, but that was all I had to do.
I have done this and the screwdriver melt down at the point where it touched the capacitator. i think its better when you slowly discharge it with a resistor. mfg Daniel
Sorry, missed it in my first read.
I was building my capacitor bank, (6 capacitors!) when I accidentally touched one while it was charged! This discharged ALL 6 at the same time! I have a small burn on my finger now. Now I wear rubber gloves when working with capacitors. :p
May caps wont charge. I've used a 9volt, and a 7.5volt ac/dc adapter. any idea why it's not charging?
Yes. They do run on 1.5 volt batteries, but, then it goes through a transformer to take it up to 330 Volts. Therefore, make sure you are using the flash circuit board to charge it. Also, make sure that you have everything the right way. The caps are electrolytic, so they have to be hooked with the correct polarities, and the first thing the electricity from the battery goes through is usually a diode, so make sure you are using the battery (or power source) the right way.
most camera circuit board are run on 1.5VDC (one AA, AAA, C or D battery). if you try and hook a battery directly up to a cap it will either do nothing or blow up in your face.
umm, maybe one is burnt out. try charging them one by one, seeing which one won't charge.
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DUH!!. but seriously folks. these things can kill. if you EVER need to open the case after you've charged the caps use a high wattage resistor. NOT A SCREWDRIVER. the pop from the driver can and will pop, deafen, even send molten solder flying. DON'T USE A SCREWDRIVER and if you do. wear ear/eye protection.
I used an iron rod, and this is what it looked like afterwards:
OK. maybe i overreacted when i wrote that. with these small caps it's not such a problem. bu if you ever "graduate" to bigger, better, higher voltage caps. get/build a proper cap discharger.
Pbyrd6 years ago
my female power connecters wont work!!!!!
Loveofchaos7 years ago
they do reuse disposable cameras. and they do get money for them to reuse them, however i have a friend who worked for a friend that now works at the costco photo spot so i asked for 6 i got 10! yay, only 8 were usable because 2 didnt have flashes but it worked, im sure if yerr nice enough u can get some. i plan to make a taser using the circuit to charge 2 200v 680uf computer powersupply capactors, i figure it will knock anyone on their butt if they try to mess with me while walking down the street. ill post an instructable on it if i can. i hope to make it tomorrow. when i can find a voltmeter ill let ya know how it works
go to wal-mart and theyll give you as many as you want without question.
Yea wal-mart is great, i went there and asked for a couple and eded up getting over 40 of them
i made iy... its sick. i might try the walmart thing tho
it's funny, I went to target and asked at the photo development booth if they had any cameras, so they went and got their manager, he thought for a moment, and then explained that they just recycle them. A minute later i was dragging home a trashbag carrying what i later found to be about thirty disposables
same here i got about 40 in a box i asked for them one day they said they had just recycled them and told me to come back a week later (which of course i did) and i ended up with a huge box of them (from sainsburys in england) great :D
i went into morrisons in england, and said i needed the flash curcuits for a 'science project' . he went out back and returned with a big white bad that had at least 200 in it and told me to help my self. they develop their cameras in the dry cleaning section for some reason, but still, i aint complaining.
i made the stun gun. its awesome. my dad wants to make me bye him a new screwdriver because i used the screwdriver to short out the stun gun. it has electrical burns and pieces of metal missing lol its awesome
pyro-jim7 years ago
i went to a place where they develop photo and asked really nicely if could have a used one and they said no because they're dangerous and they have to be thrown away
They Must of been those irritating adults who think that all kids are stupid and will kill themselves with it. They assume that you know nothing and will either dischare all capacitors with a screwdriver or their fingers. I am not saying that they are not dangerous. what i am trying to say is that if you respect them and take the required safety mesures you should be fine.
n3ldan pyro-jim7 years ago
actually they should be recycling them. generally if they turn you down you can explain your purpose, and once they realize that you know what you're doing and you're not just going to shock little kids with it they'll give you some.
i'm not going to shock little kids with them? *shifty eyes*
Pbyrd7 years ago
Also could you please go into detail about the coil winding? I am in the dark about it.
kalika237 years ago
Great instructable, i will be making one of these tomorrow after school! =D

i have one question though... about how many volts is each capacitor?
They each store 330v and its printed on the side of the capacitor itself if you're planning to go and buy some. So you will know exactly what to get
PyroMonger7 years ago
can u elaborate on the coil winding. Show a picture or 2 of it being done please. thanks.
Mine doesn't work! I did this and it didn't work! Well it does work but just BARELY! :( When i put the projectile into the coil/barrel, and turn it on and press the button, it just barely gets out of the tube! Instead of using only 4 capacitors, I used 5. But wouldn't the extra one give it MORE power? I also only wound 9 layers of wire instead of 10... Could this really effect it THAT much? PS: How powerfull is yours?
i had that problem, and it was the coil. i wound a layer on the bolt, put tape on it, and wound another from the same place working the otherway, got to the end, put some more tape on, and wound back again. you must wind a layer on, then go back and wind another layer on starting from where you did last time, if thats the problem.
Yup... I figured that out after days of frustration. :(
cris11337 years ago
very stupid question :whats a coilgun?
AlfonsVH (author)  cris11337 years ago
A simple google-search for the word "coilgun" will yield about 58.000 results, with a nice wikipedia-definition of a coilgun as the first hit; "A coilgun or Gauss gun is a type of projectile weapon that uses one or more electromagnetic coils to accelerate a magnetic projectile to high velocity"
Thorolf7 years ago
it would be awsome if you included an electronics diagram of the project.
Wolf Seril7 years ago
How far does it shoot and how powerful is it?
i think the power supply connectors were a good idea because u would run out of batteries pretty quickly since u got all those capacitors leeching the power out of 'em
pyro-jim7 years ago
for the barrel that you wrap the coil around, could use use metal or would it not work?
n3ldan pyro-jim7 years ago
you could, but eddy currents will decrease performance, though IIRC if you cut the tube lengthwise it helps to reduce them. use a plastic straw or bic pen tube as suggested.
Wait... So how long should the coil be? 2.5 cm or 2-5 cm?
AlfonsVH (author)  Einsteins Circuitry7 years ago
Two and a half cm
ummm... im having a bit of trouble here... if I'm using a universal circuit board... do it matter where i solder the capacitators or are there particular coordinates... i know im not very good at this stuff either...
paulm7 years ago
I made a cannon shaped one, when I asked for some cameras they gave me 12 (i've only used 1 so far) that and I own a 300v 1000 m-somthingrather- capacitor, so im all set. would all i have to modify in my design be wiring capicators in parallel and getting a better switch (aka rated for like 1000 volts)?
evilboy94947 years ago
I was just wondering were to get free disposable cameras???
o yeah im askin if this would work taking the long metal peice and solder the capacitors to that the a wire the solder the wire to the lead of the other capacitor
um can you just attach the capacitors to wires then attach them
ok i looked there and i will do those things but at the page 3 instructions it say a universal curcuit board??? what is that ty
Killa-X7 years ago

Ok does the coil + - tips connect to where the flash use to be? Cuz on my thing i had the camera charger build up the caps, and the other side, the caps went to a button, that lead to the coil.

Cuz I heard removing the flash on the newer cameras has this ghost thing cuz it kills the board..
Awsome! I'm going to HAVE to build one of these babies.....
bumsugger7 years ago
Hey Ramses, care to add a circuit diagram so we can ALL get it right??
ramses7 years ago
some other comments. scratch the low ohm resistor. and the little push button switches at radio shack are rated for 3 amp at 120 volts. this is at least 150 amps at 300 volts. right now i use a flash tube from one of the old camera flashes i bought at a flea market. works well. i do have a large coil. if that was bypassed, i have no doubt that the tube would explode. a SCR is your best bet. hook up one end to the coil and the other end to 1 side of the cap, and then hook up the 3rd connector to the - of a 9 volt, the + of a 9volt to a switch, and the wire from that to the anode (+) push the switch to dump the caps. A REVERSE BIOS DIODE IS CRITICAL!!!!!. you will blow your SCR if you don't. 400v reverse breakdown, and 10 amps should be good. if you can't find 1 with the amps, put 'em in series. or just touch 8 gauge wires together lol
Um this is awsome but I'm kinda wondering when you connect the capictors to the coil wouldn't it short out the capicitors because in a way they're connected + to -.
no they are hooked (+) to (+) and (-) to (-)...i think...
Noooooooo....a series is always wired (+) to (-), other wise it will surely not workk
AlfonsVH (author)  crreed7 years ago
The capacitor string is made out of parallel-connected caps (+ to + and - to -) ;and the string as a whole is conected in series with the coil.
Connecting caps in series doesn't make much sense, because you lower your total capacitance by the reciprocal of the sum of 1/F.
english please???
AlfonsVH (author)  girrrrrrr27 years ago

This is as English as it gets... You do not need to know everything about electronics to be able to build this device, but basic knowledge always helps.
ok i will use my basic knowlage to make this...but i am stuck it wont charge while i have the coil attached...i have tried 3 different circut boards and they wont work... i am hookimg the coil to the flash what am i doing wrong... i also have the switch hooked up to the trigger that activates the flash...
AlfonsVH (author)  girrrrrrr27 years ago
Quite hard to tell, but, if there is a small capacitor on the circuit board, try removing it. That may help.
ok i will do that...
oh and i only have 3 capisitors hooked up and my flash charging switch is pressed...and i am using normal copperhead bb's... i have 40 ft of wire with washers on eack me!!! thx...
a capacitor stores up its charge on two plates inside of it . these are separated by a NONCONDUCTING layer to prevent shorting and make the thing work. hooking up in series means you are trying to run the charge through this insulator.
crreed crreed7 years ago
Have you tried wiring the capacitors in a series? seems as though that would be much more effective
AlfonsVH (author)  electronicfreak228 years ago
I see what you mean, but the coil in this case acts as some kind of resistor (with a rather low resistance)
moza7 years ago
my coilgun only shoots about 9 feet... how do i make it shoot farther...i tried more capacitor but it did not work... amplifier... how
moza7 years ago
If i have a SCR wat do i connect the 3 wires to if im making a coilgun?
add this to my group electric shock
moza7 years ago
every thing works expt the wire for some reason... any ideas
Namlem7 years ago
what do the two little boxes say? I can't see them because of the big box.
if you're intending to use a coil of significant inductance, you might consider putting a reverse-protection diode across the capacitor bank. that'd be a good idea in any application where large rolled-media caps are discharged completely into a given load. you should also be warned that using a switch for a trigger on this is usually going to eventually result in the output terminals being engergized through the conductive tracking and sputtered film which is formed inside the switch when contacting under such conditions. i've gone so far as to use a mercury switch in my portable hot-boxes. i can't really recommend this due to the danger, but it does illustrate the benefit of a renewable contact surface.
dumdog9277 years ago
my kodk came with a press thingy button to make it charge ho can I ive it a different switch+
ramses7 years ago
Schematics and graphs
graphs.bmp06-05-2007 04;16;35PM.BMP
DIY Dave7 years ago
I thought they reused those desposable cameras.
ramses7 years ago
i am sorry but this whole thing seems totally screwed up.

i saw some1 post that series is better. you get no more energy due to the conservation of energy which states that energy can't be created or destroyed.
it is, i my opinion, better because it allows for a shorter rise time, but since the circuit board doesn't charge to 3kv if you used 10 caps in series, each cap would have the voltage of 300*10= 3000 volts at a lower capacitance 1/(200*10)=.0005uf which would go into the formula E=c*v*v/2 to be E=5*10-10*300/2 and E would be2.25-5 or .0000225 J, enough to accelerate a 1 gram projectile at 100% efficiency ( as opposed to the >1% likely) to .048 fps. the force wouldn't even be enough to break the static friction of the bb of come close to opposing it's inertia. if you had a 3kv charger, that would be great, but that would also make it 100% LETHAL, where 300v at 2000 uf is only if you grab both wires on opposite hands and squeeze. touching them would only cause your grip to tighten by stimulating your muscles, thus decreasing resistance, and allowing more current to flow, while discharging the caps.

External iron draws the magnetic flux closer to the projectile, increasing strength, but compromising inductance, and therefore peak currents, and rise time. this is unimportant because if the current is gone before the center of the projectile is in the center of the coil, and it isn't, say the 5the coil in a multistage coilgun, which is so complex i won't bother explaining it.

make sure that the cap bank ( + to + and - to minus) is connected with the right polarity, and is in series with the big switch, and coil. if it isn't in series with the switch, you are constantly shorting both the caps and the charge circuitry.

also, try using a ~300v diode band (once again in parallel) connected so that it doesn't conduct when the big switch is pressed while the coil is removed. a 5ohm resistor in series with the coil is also a good idea to ensure that the LC oscillator is shorted through the diode bank at the half wave mark, reducing suckback. the diode- resistor mod will decrease performance, but will prolong the life of the capacitor and charger.

"super capacitors" are horrible for anything, except long delays, and sustaining volatile memory in computers. don't use them because farads aren't everything.

turns doesn't matter, because they are linearly related to resistance, which is inversely related to current, and since they are both to the first degree in the coil strength formula( the one that i don't have memorized), they cancel each other out

sorry i hijacked this post, but it was bugging me that the comments were so false. the resistor in parallel alone would have to be precisely chosen so as to not "over dampen" the circuit, resulting in a inverse exponential decay 3kv would overload the switches anyway.

I hope to post schematics soon
AlfonsVH (author)  ramses7 years ago
Thank you for your input, ramses. Finally someone who can really tell something about electronics. My knowledge is too limited to give any decent information, I guess...
vince0867 years ago
Hi, I wanted to know were i could get some enameled magnet wire (ca. 0,5mm diameter) and the same universal circuitboard that you used. And can i use difrent types of capasitors to make th coilgun?
AlfonsVH (author) 7 years ago
I'm not quite sure... I bought mine at Velleman Belgium.
RPisces7 years ago
Ok. According to this instructable, I am assuming that the maker gets VERY low performance. I doubt that the projectile goes that far. I made a very complex one of these with 15 330V, 120uf caps in parallel, and the nail I used only went about 7 feet. Then I hooked up a 400V, 3900uf cap (Nippon Chemi-Con) to the circuit in parallel, made SURE that the nail was situated JUST in front of the coil (shoots better when it is just at the beginning of the coil), and charged the thing with 4 AA batteries. The nail STILL only went 7-10ft. This should answer QUITE a few questions...
AlfonsVH (author)  RPisces7 years ago
I already mentioned how far my projectiles go et cetera... The performance of the device is not only dependant on the type of capacitor used, but it's the capacity+discharge time:coil-inductance ratio which counts. I think you should stop making assumptions without asking me first.
(removed by author or community request)
AlfonsVH (author)  RPisces7 years ago
I do indeed have only a little bit of electronics knowledge; that's why I can't answer your question ;-) I only know that the inductance of the coil matters, as well as the capacity and discharge time of the capacitor. I'm not quite sure how to calculate it, though, and that's why I wasn't able to maximize the performance of my device.
vince0867 years ago
Do you stil sell the kit? And should the coil be one long wire or should it be a sigle peice of wire per layer and then conect the wires to one thick wire that goes to were the flash-tube was connected?
AlfonsVH (author)  vince0867 years ago
I'm sorry, I don't sell the kit anymore. The coil should be entirely made out of one piece of wire; so wind one layer, and just "turn back" with the same wire.
vince0867 years ago
how far does the load go,eg: a small nail?
AlfonsVH (author)  vince0867 years ago
Not that far with the device I made. I guess about 5 or 6 metres, but I'm quite sure that if you make proper calculations as to amount of coil windings et cetera, you should be able to get much better results.
dumdog9277 years ago
Dazzaa8 years ago
what does the wire connected to the reflector actually do?
AlfonsVH (author)  Dazzaa8 years ago
To be honest: I haven't got a clue. My electronics knowledge is limited to the real basic stuff. I don't use this wire; just cut it off.
...i am just going off of what i found in my weeks of research...
Dazzaa AlfonsVH8 years ago
when i tried to make a stun gun out of a disposible camera i did that, and removed the flash bulb, but then the capacitor wouldn't charge
AlfonsVH (author)  Dazzaa8 years ago
Hm that depends on the circuit board you're using. Sometimes you also ought to remove the triggering cap or transformer to allow the cap bank to charge.
ll0ll8 years ago
does it have to be enameled magnet wire? Where can I buy some in the uk?
AlfonsVH (author)  ll0ll8 years ago
It does not HAVE to be enameled, but if it's not enameled, you should isolate each turn with electrical tape or so, so I would surely recommend using enameled wire. It should be readily available in any electronics store; I'm not from the UK myself, but I'm positive that it's sold there. Just ask the seller for "coil winding wire" or so.
or you can ask for enamled copper wire...i think it is the same...or at least it looks the same...
i'd suggest try an electronics hobby shop, like one of the ones that derals with remote control cars and stuff.
x_pyro8 years ago
Is it true about the more turns u have on a coil the stronger it is?
yes up to a point...the more turns you have do make it stronger but not enough to make you want to make a 400ft wide coil...but if you want to make it stronger than you would want to put a few washers on the end and wrap it in steel...also make sure they are steel washers... and more power makes more strength... i think i am correct...
x_pyro8 years ago
Couple more questions. 1. if i wanted to use a project box instead of what u used what would be the measurements of the box. 2. i still don't understand how ur hooking up the battery to that other stuff 3. do i need to buy both of those switches that you did ot is that unessesary 4. i also still don't understand how you are hooking up the capacitatiors to that other chip that you showed they were on
1. large...but not to large... you can also put it in anything you want can use bigger and use more stuff in it... 2. you hook up the battery the came way that it came out of the camera...he just wanted a faster charging...i think... 3. no you dont need both of teh can just re-route the ones that you had before... 4. he hooked them so that they were(+) on one side and (-) on the other... this advice is just if you are using a camera circut...
x_pyro8 years ago
I have a couple questions about this, but could u e-mail your answers to me please at 1. would i be able to do this same thing with regular disposable kodak camera 2. what are u useing to case the components 3. what do u stick in to the power supply connectors? 4. i don't understand completely about connecting the capacitators (i mean connecting them throughout the whole project)and with the circuit board u used 5. finally where did u get your desoldering pump Sorry about all the questions. I kinda new at this so ui'm just triying to celar some of this stuff up.
5. you can get a desoldering pump at radio shack... 3. you can stick a battery in the power supply... 1. yes you can do the same thing with the regular cameras... 2. he is using a plastic case...but you can use long is it is big enough... and last but not least... 4. you need to conect the positives together and the same with the dont have to use a circut board you can just use 2 long at they can take the voltage rating... hope this helps... -one who annoys but in a good way
nice have you tried a pellet or a bb?
AlfonsVH (author)  Jack Daniels8 years ago
I have, but for some reason that doesn't work. The projectiles have to have a certain lenght.
xerox AlfonsVH7 years ago
I think thats because the magnetic field needs something longer to grab onto
a BB will work...but a pellet wont...becuase lead wont attract...
richo_137 years ago
when choosing capacitors for a coilgun, is the voltage rating or the capacitance rating more important?
AlfonsVH (author)  richo_137 years ago
They're both things to take into account. You want a high capacitance to give a strong pulse through the coil, but you have to make sure that the capacitors can handle the high voltage which is supplied by the camera's flash circuit. I guess the best caps to choose for a first-time build are the so-called photo-flash-caps, which you'll find inside cameras.
markf AlfonsVH7 years ago
If you were designing a pulsed-power device from scratch, you would want to favour voltage all the way. Stored energy increases linearly with capacitance but it increases as the square of voltage. So 2x the voltage gets you 4x the power. And of course, discharge time increases linearly with capacitance -- you need all of that power to discharge in 1 millisecond or less if you're going to get any real speed, so low capacitance and high voltage is the order of battle. That means connecting caps in series, not parallel. But the photoflash caps are already a good high voltage (300v to 400v), and the transformer can only take the voltage so high (usually 200v), so for this kind of project you just want to connect lots and lots of photo-flash capacitors in parallel.
I can get 400V 3900uF capacitors off eBay. Would 4 or more of those make a good coilgun?
markf richo_137 years ago
Assuming that:
  • the camera's transformer charges the caps to 200v (which is the voltage requirement of the bulb)
  • the projectile weighs one gram,
  • only 1% of the energy will be transferred to the projectile as velocity (even 1% is overly optimistic),
then the projectile will be travelling at about 79 meters per second, or 284 kilometres per hour.

That's my back-of-the-napkin calculation. Michael Faraday is probably spinning in his grave and will no doubt give me a good haunting for doing such laissez faire calculations, but there you go.
so how fast does this bad ass coilgun shoot?
AlfonsVH (author)  pyroskater80047 years ago
It doesn't shoot that fast (I guess about 35km/h); but that's mainly because I didn't tune it.
If you make the proper calculations (how many coil turns etc...) you should be able to get much better results.

A good place for formula's et cetera is the forum of
Beelzebub8 years ago
the circuit is the easy part, the coil makes all of the diference in how the gun fires. i was actually in the process of making an instructable on this when this came out :(
AlfonsVH (author)  Beelzebub8 years ago
Indeed, the winding of the coil is very important. My coilgun did work, but the performance was rather low, and I expect the coil to be the cause.
how hard is the projectile shot? does it do any damage?
I think you should release that too, it would be better to have two coilgun istructables it may give people a better understanding of how they work
AlfonsVH (author)  Dazzaa8 years ago
Indeed; it's not because there's one instructable about a coilgun, that there shouldn't be another one!! I certainly recommend making it anyway!
matejj7 years ago
Is it essential to put a diode before the coil and a resistor after the coil to prevent caps from exploding since they are polarised caps? And what kind of diode and resistor do i need for a 500uF, 330v cap?
NumberX7 years ago
I have wondered how coilguns work.
AlfonsVH (author)  NumberX7 years ago
I suggest you to google for it. There's extremely much information available on the internet.
Thanks for the tip, now I understand how they work.
x_pyro8 years ago
Also if i was making my own coil without the disposalable camera chip thing, what kind of resistor would i need, IF i needed one.
AlfonsVH (author)  x_pyro7 years ago
If you want to do such a thing, you'll have to make your own charging circuit (for example using a 555 timer IC). Google will give you many valuable resources (just use "555 coilgun" or something as the search query)
AlfonsVH (author) 8 years ago
I just discovered that someone made a Digg entry of this instructable. Be sure to digg it at !
spacessj8 years ago
ok I asked my dad(he studied electronics) about the discharge time and he said the only thing that influences it is the resitance (in this case a coil). If this is correct, is this then possible and useable?
2*330uF 220V
1*330uF 16V
3*220uF 16V
1*220uF 25V
2*100uF 16V
1*470uF 16V
3*1000uF 10V
1*3300uF 10V
1*3300uF 16V
total capacitance=12140uF
max voltage=10V
westfw spacessj8 years ago
Capacitors have an "internal resistance" as well, that tends to go up with the capacitance. So a 3300uF cap at 10V will take longer to discharge (everything else being equal) than a 100uF cap at 300V (which is about what's in the usual flash.) Also, the energy stored in a cap is (1/2 * C * V*V), and that V-squared term means there is a big advantage to high voltage caps. The 100uF 300V cap holds about 5J of energy. The 10000uF 10V cap holds about 1/10th of that.

Still, we're talking "demonstration of principal" here, rather than "weapon of maximum efficiency" (capacitor energy density is about 1/500 that of typical chemical fuels, according to I doni't see any reason that you couldn't make a low-voltage demonstration coil gun. It would certainly be a lot safer to poke around...
spacessj westfw8 years ago
ok thanks. are the 3 1000 and the 2 3300 uF caps plenty or are the 2 330uF 220V better(for demonstration). Id' like to power a railgun as wel using (the) cap bank.
Lemon8 years ago
Projectiles: For this coilguns' dimensions, about 15mm in length is optimum (to the best of my knowledge). The thing is with a coilgun, since it uses a magnetic field as its "propellant", the more metal a.k.a projectile there is to attract and pull on, the further it will fling it. Also cylindricle projectiles (like nails with the points ground off) are best. The photo will help explain.
coilgun projectile theory.bmp
spacessj8 years ago
other question: I can't get my hands on disposable camera's but i do have some caps from a computer power suply. I have at least one 1000uF and one 3300uF cap (1 is 10V the other 16V). I also have some smaller 330uF's but 2 of them are 220 V ones. Will these work and how do i charge them? oh and can they also power a railgun?
AlfonsVH (author)  spacessj8 years ago
I don't think computer caps are applicable since they aren't meant for fast discharge. The voltage is way too low, too; so I guess that wouldn't work. I think it should be possible to build a railgun using a similar method, but you should google for it to find more information about that.
what are the specs of a flash cap?
AlfonsVH (author)  spacessj8 years ago
Typically they're rated ca. 500µF, 330V or something and they're labeled 'Photoflash'.
See for some more information about the difference between photoflash caps and normal ones.
spacessj8 years ago
nice. About the coil: is it one pice of wire or is it one piece of wire per layer like here:
oh and does it matter how you connect the coil?