Help with caps for mini coilgun?

[tomcat]

iv got shocked too.. i was quite young (13) at the time and i passed out... was playing with one taking it apart and linked 10 in parralel (200v 450uf i think) then they shorted arm to arm though my chest... woke up in ambulance with sirens and everything and said "dude tha' hurt oi fatha im fine tell the ambulance dudes to stop the noize givvin me a 'ead ache" can ye tell im from yorkshire

 

[Switch]

DAYUM....Through your chest huh? :-? You're pretty lucky you survived....Are you sure you didn't wake up after they hit you with the defibrilator?

 

[tomcat]

no they just gave me a shot of adrenaline to make sure glad i was out i HATE needles broke the last "doctors" (male nurse really lol) nose and took out 5 of his teeth... when he came at me with one (tb jab)

pretty sure im not brain damaged 4 years later... i think.. what was i typing

 

[Abray]

ok I have just looked into making one of these. I don't know too much about capacitors and coil guns, but I think with help on here I can get one done.

just some questions about parts:

1) Is it better to have many medium sized caps (200v 450 uf) or one large cap (the ones that are like 15000uf)?

2) What size wire should I buy, and about how much?

3)what kind of power supply will I need?

4) I know that the amount of time that the current goes through the coils needs to be very small, so what kind of firing device will I need?

 

[Switch]

After I did some more research, I came up with the following tips:

Doesn't matter if you have many small ones or a huge single cap.Only the total capacitance and voltage of bank.
Discharge time must be short to prevent suckback effect, but long enough to achieve decent acceleration.Discharge time is inversely proportional to capacitance, so you need small capacitance.But to keep energy stored in the capacitors high while having small capacitance, you need big voltage.(so for example 1000V 1000uF is better than 100V 10000uF even though same amoun of energy stored).
Higher voltage is also better because it means higher current through the coil.And higher current through the coil = stronger magnetic field.

Now the coil: Wire must be thick enough not to melt.(I think that's the only thing where thickness matters)
More turns = stronger magnetic field BUT more turns also = higher resistance = less current = weaker magnetic field SO you have to make some sort of compromise that works best for your capacitor bank.

Power supply should be able to charge capacitors close to their V rating.And as for trigering I don't really know the requirements for a big coil gun.For a small one you can just connect a switch in series with the coil directly to the caps.I saw people building larger ones that were using SCRs to discharge.Now I have no idea how SCRs work :-X

 

[jamilm9]

i got a 5.5 volt cap with one f

 

[rkcstr]

I repeat:

I have a couple 450VDC 3700uf capacitors, they're about the size of a Campbell's Chunky soup can each.  I'm sure those would make a nice spark.

Also have some 40V caps of 13000, 25000, and 51000uf.  Also huge.

They all have screw terminals, so you can hook up heavy gauge wire easily too.

I could be convinced to let go of them, if you're interested  

I believe if you wire them in series you get equivalent 900VDC 2350uF capacitor... I think that's a pretty good zap  ;D

 

[jamilm9]

i have a cap which is 5.5 volts and 1 f