for a coil gun is it better to have high current or high voltage?

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Plasmana8 years ago
It depends on the build of the coil. If the coil has a very few turns of thick wire, then low voltage and high current is suitable. If the coil has many turns of thin wire, then high voltage and low current is suitable.

if ur still on instructables I have a design question for you plasmana

Since your talking bout coilguns, Is a coil with many turns of thin wire suitable for a second stage (after an injector) or a coil with very few turns of thick wire, Which is more suitable?
Hmm, that is a good question, I never built a coilgun with two or more stages, so I don't know which wire would be suitable...
Oh, Thanks anyway Plas.
Wesley6668 years ago
I heard something about this somewhere. High voltage gives you higher speed but less power and high current gives you more power but less speed on the projectile, or something. All I know is that there is a trade off.
.....that's not possible..... the speed dictates the power. What is more likely is it is probably like a motor with gears scenario. You can move something small very quickly or something big very slowly and you want to match your gears to the optimal speed while still being able to carry the load.... But biased on my knowledge of electricity I don't think that is how it works either.
The speed of the projectile dictates the energy of the projectile at a given weight. It all depends on the wire in the coil, the number of turns, how close those turns are, the material the armature is made of, the size of the projectile, the weight, and the length. Sometimes you can just make a longer armature (projectile) to use up more energy while it is entering the coil, it takes more EMF to pull a longer armature in. You want to completely use up all of the power at the half way point so the coil does not try to suck back the armature. This longer armature (projectile) will have more mass, so it will have more energy, if it is moving at the same speed, or hopefully faster. A rule of thumb is that the armature should be about equal to the coils length, but it all depends on what makes up the coil. if you add more capacitance or more voltage, you armature will be effected differently by the magnetic field because the field is changing characteristics. The coil the armature and the power source are the 3 main ingredients to a successful coil gun good luck.
afehr4 years ago
I have a question? I thought about taking the capacitors and 40000uf 200v.
And as a circuit using a flash, it can go?
(sorry if you do not understand what I wrote, because I used google translator because I speak Italian)
Thanks in advance: D
Wesley6667 years ago
What would be the best is a multi stage coil gun.  The first coil could be high current low voltage and a second coil right after high voltage but low current.  Multistage guns are harder to build because the timing to switch the power from one coil to the next has to be fast and timed properly.
nidobrito8 years ago
Depends...but in generals high voltage....because if have a high voltage have a big current.....[ ohm law XD
High voltage isn't necessarily high current, For example a NST puts out about 15000 volts and 0.02 of an amp...
but in this case is because we have a capacitor....
Yeah, Which can be either low voltage and high current or mildly high voltage with high current
Yo! but in high current (in case of capacitor discharge) the current is much more than a low voltage....XD \o/
Current IS amperage. Voltage has nothing to do with current, except that, when multiplied by voltage, you have the VA (apparent power) of the system. The reason it is apparent power and not real power is that it doesn't factor in phase angle.

When you discharge a high-voltage capacitor that is the same physical size as a low-voltage capacitor, chances are you'll get less energy out. The reason for this is that the capacitor will take more insulation (dielectric thickness) to make it so that the capacitor doesn't burn a hole in itself.

When you have a 10KV capacitor rated at 1µF, it has the same power as a 50V 40,000µF, just at a higher voltage. Guess which capacitor would cost more. I'll give you a hint; higher-voltage capacitors tend to cost more than polarized electrolytics.

Just some food for thought. Perhaps you should look up the formulas before assuming that your own perception is correct. That has made me have many experimental failures in the past.

If you'd like to verify my math, you can use the formula Joules=(C*V2)/2
Joules = energy stored.
C = capacitance
V = voltage the capacitor is charged to

Have fun! =)
Wow, You're pretty good, Since you know a bit about coil guns, Is it better to have the first stage having thicker magnet wire and less turns or a coil with thinner magnet wire and more turns? I have a coil with thin wire and about 12 layers whereas the bigger coil I have has about 16-18guage, thicker wire with about 3 layers. What coil should I have as the first stage and which for the second stage? I also have an injector coil...
What you really need depends upon the capacitor type you are using. A higher voltage rated capacitor will discharge more quickly and, for that reason, is better for the second, third, fourth etc. stages, whereas, for the first stage, it's better to have fewer turns and a higher capacitance, lower voltage capacitor. You want to get it moving with the first stage, and a high capacitance will make it move because of the similar magnetic field density over a longer time. You'll want to make sure that your wire can stand up to the discharge of the capacitor..... If it can't then you'll end up not looking so great, anymore. You may even end up in a morgue. Be careful.
Well I have a cap bank, about 300v at 1000uf, I also have about 10 photo flash caps, So I will make a smaller bank with them... The coils can both stand 300v at 1000uf, So I think they will survive...
lol it's relative.....but for a injector coil use a coil with a thin mag wire to make a little but strong coil and discharge only a little cap(a flash cap will be OK) to change the inertia state of the bullet...the next stage use a thicker wire to make a coil for big currents an with low resistance....
and i know the formula of energy stored in the cap....
lol I know this man..I'm working in my coilgun since begin last year...i suggest use a high voltage cap because they apparent power is higher an the losses of energy will be low if compare with the low voltage.........but have the disadvantage of the insulation(need be more strong)..... and a higher voltage will affect the suck back effect and increase the efficiency of the coilgun.... if the apparent power is > than the real power of capacitors they will discharge more fast on the coil generating a more strong magnetic field