RAIL GUN capacitor size/power questions???

[supak111]

Hey everyone, I'm thinking about building a mini mini rail gun, got a few questions about capacitors.

QUESTIONS:

1. Whats better for a rail gun: using higher voltage capacitor or higher uF? example: is it better to us 1 x 1,000,000uF 5volt cap, OR say 1,000uF 5000v cap?? Power comes out the same but what better?

2. Which of the two above would charge faster if I have MAX rate voltage coming in both? Anyone know how fast?

3. Safety, if a capacitor is only 5volt x 1,000,000 is it safe to touch both leads since its only 5v?? I would or would NOT get shocked? And the 5000v I KNOW NOT TO TOUCH but if I did could it kill me?

(I like higher uF because capacitors are cheaper and smaller, I'm thinking they got to charger way slower tho)

 

[BobK]

A capacitor charged to 5V could only kill you if you try to swallow and choke to death.

A large enough capacitor charged to 100V could give you a fatal shock.

One charged to 5000V (you won't find any at a reasonable price) will likely kill you unless you are very cautious.

Bob

 

[supak111]

Thank for the answer, any input on my question #1?

 

[(*steve*)]

Energy = 1/2 x C x V^2

Power does not come out the same!

 

[supak111]

Energy = 1/2 x C x V^2

Power does not come out the same!

Thanks for the formula, I needed that. Say those two were the same power output, whats better High V or High uF?

 

[(*steve*)]

Say those two were the same power output

Are you sure?

1,000,000uF 5volt cap, OR say 1,000uF 5000v

25kj vs. 25j Hmmm...

Only only of these will kill you -- probably by blowing large chunks off you.

 

[supak111]

I get that they are not the same now. You are still missing my question. Take 2 that are same, I just want to know what is better, high F or high V.

 

[(*steve*)]

It depends on the impedance of the device you're driving.

You do realise what happens when you discharge a capacitor into an inductor, right?

You can't design one part in isolation from the others.

 

[supak111]

railguns doesn't use any inductors.

 

[(*steve*)]

Really?

What do they use?

(Don't say "electromagnets" or I will point you to an explanation demonstrating that electromagnets are inductorshttp://en.wikipedia.org/wiki/Railgun)

(And also don't say "not electromagnets" or I will point you to a description of a rail-gun as a type of electromagnet)

 

[supak111]

I'm a newbie man I'm not here to argue about what they use but I'm here hoping to get help on best parts to use to build one lol

 

[BobK]

You do realise what happens when you discharge a capacitor into an inductor, right?

That rings a bell!

Bob

 

[jackorocko]

wait, is C a value of Farads? Isn't microFarads 0.000001 of a Farad? Then how is it 25kj and 25j? My calculator says 12.5

supak111, as steve has pointed out. Power is not the same, so the price point for smaller voltage caps is moot because you will need more to get the same power output. Maybe you should first figure out how much power you require first?

 

[timothy48342]

A coil gun is the one with stages of coils to pull a ferromagnetic slug along.

A rail gun uses a conductor sliding along 2 straight rails. The payload in this case conpletes the circuit until it launches.
-t

edit:
ok. I see your "railgun as a type of electromagnet" and I raise you "coilgun uses something more similar to most electromagnet we come across."

:endEdit