Instructables

Disposable camera coilgun

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

soldering-cap-array.jpg
circuit-board.jpg
- 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.
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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 jdorne3 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 jdorne7 months ago
Where in the world did you get a 55 farad capacitor!!!!!?????
jdorne Nilpmet7 months 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:

http://www.instructables.com/id/DIY-How-to-make-a-coilgun-from-disposable-camera-/

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)  electronicfreak227 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?
jbussé2 years ago
+32 number that ought to be BELGIUM !! hallo mede bewoner van het regeringsloze land :D
AlfonsVH (author)  jbussé2 years ago
Aangename kennismaking lotgenoot!
Hoe lang nog, gewaardeerde zuiderburen?
AlfonsVH (author)  diy_bloke2 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...
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