advice on making a rail/coil gun also known as a electromagnetic accelerator for someone who understands basic electrics

im looking for advice on how to make a "rail/coil gun", i understand the principals behind it and the componets needed but id like to know what is the most efficent and powerfull componets. have in mind im looking at making the gun completly portable but a stationary charging for the battery would be prefered

id like to keep the device 12v dc if possible using a battery to charge up capacitors, a switching device which allows the capacitors to charge and switch of the battery input automatically to prevent the electricity draining back into the battery. also another switch which discharges the capacitors into the coils but is switched manually(trigger), multistaged coils hopefully around 16 if possible( the way i see it lots of power running into lots of coils means the projectile traveling faster and further) ive also been told that once the coils have been charged they'll need to be discharged within micro seconds and theres a certain componet which allows that im not sure exactly what that is?. Having many coils means ill need a timing mechanism to activate the coil when the projectile is within the magnetic field, ive done a bit of research on that and come up with a microswitch between every coil or infared diode and a photosensitive diode(not sure exactly the name of the second one).

1. how many rows of coils would i need for each coil, what gauge wire would best suit my needs, what grade of wire, a way to prevent the magnetic field affecting the coils next to it, to optimize the energy in the capacitors should i start with a larger gauge wire at the first coil and slowly decrease it per coil,

2. what size capacitors would best suit my needs also bieng small in size, also would it be better have 1 or 2 capacitors per coil

3. what sort of switching device would be best for charging the capacitors and isolating the battery when there charged

4. is there another switching device for turning on each coil seperatly when the projectile is in range of the coils magnetic field to optimize the use of the magnetic field

5. more info on when the coil needs to discharge would also be great

any ideas or inputs would be greatly appreciated no matter how big or small or if only concerns a certain aspect,

cheers, chris cross australia


Wow that is a heck of a lot of questions, I will attempt to answer some of them. It appears that you want to keep the power at 12v, but that might not work very well for your coil gun. In order to get a high power system you would have to use a higher capacitance. It’s a trade off amps or volts. I would suggest at least 300 volts, but don’t get me wrong you can build a low voltage coil gun, I have made one with a car battery. With the exception of maybe 3 coils, multi-coil systems do not add that much more speed, the first one gets the initial speed and the second coil speeds it up slightly, the third or more coils only add a fraction of speed. Any way on to your numbered questions: 1. It all depends on the armature(projectile) and the power source. For high amps I would suggest a thicker wire, like 12, 14, 16 AWG. You can get a good idea of what you will need for a 12 volt system by looking at automotive solenoids, go to an auto parts store and ask for a ford truck or car starter, on this ford starter there is a solenoid, ask them for this solenoid, it can be had for about $20-$35. Make sure they do not give you a starter relay, That has smaller wire in it. The one I am referring to is attached directly to the starter. By taking this apart you can learn about how you should put yours together, the number of turns and the gauges of wire to use. These are also a good source of magnet wire. You should be able to build coils of the same gauge wire, but it depends on what size the capacitor bank is for each stage. 2. The size depends on the power you want, and what voltage they are. If you are sticking with 12 volts get at least a farad, but I have seen bigger ones, and banks up to 18 farad on ebay. I would suggest starting with a 1 farad, because I do not know the size and weight of the projectile, or the coil you will design for it. An armature is designed for a coil, and the coil works best at a certain energy at a voltage. A better question for #2 would have been: I want to shoot a 9mm 5 gram projectile at x speed(or x distance)(or through x material). 3. If you are using just 12 volts I would suggest an automotive 12 volt relay, or a starter relay, this would be cheapest, you can also move to solid state switches if you have the money, an SCR is a nice start and can be had for $5-15 on ebay. 4. Once you have decided on the coil, and the cap bank this will dictate what switches you should get. For a multi stage I would suggest sold state, such as an SCR, regular transistors, and IGBTs. You should use a separate switch for each stage, and I would suggest optically triggering them. The coil and capacitors will work best when designed for each other. There will be a voltage or capacitance that will give you the best speed, and it also depends on the size of the armature. 5. When you get to a point where your first coil is shooting well, the optical sensor should be set up and the coil moved or the optical sensor should be moved, I would suggest a few inches, maybe 4 between the coil, and then move the optical sensors till the speed increases. You will have to see how fast that second(and additional) coils are able to create a magnetic field. If your projectile slows down move the optical sensors closer to the previous coil. I hope I have created more questions for you to ask, there is no singe way to do it, I find it best to learn about each component, and just dive in and experiment. Concentrate on your first coil before you go all out on a multi stage system. Try out what is already available, and research other people’s coil guns, such as on this site, and the world coil gun arsenal.
crossy (author) 7 years ago
yeah i have but nearly all of the results i get involve using a flash camera and there only basic designs hopefully someone with a bit of experiense with electronics can point me in the right direction, abit of conformation that ive got the right idea and heading in the right direction would be much appreciated
kelseymh7 years ago
Did you try searching Instructables for either "rail gun" or "coil gun"?  You might also try looking on Wikipedia or even (shudder) Google.