# COMMUNITY : FORUMS : TECH

## 12kj coilgun project

Hello I am working on a new coilgun using 15 10000 uf 400v 17200 ma capacitors. The accelerator is 5 stage, while using 3 caps per stage each stage will have 2400j of energy. I will be posting updates on this forum every month or so.
my current setback on the project is charging
what I am wondering is what input current and voltage and output current would I need to charge 3 caps decently fast.
once that is solved I will line up 5 in parallel to charge all (1 per stage) if I need to line up a greater amount of a lower rated circuits I will.

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dudes2 years ago

So for a set of three caps (3x10,000uf) to charge in 30 seconds you would need a power supply that can output 360v at 360mA. More amps would mean a faster charge. Although the supply needs to be able to output 360mA, it would actually be charging the caps with closer to 130mA, I'm still not sure about the details of capacitor charging and how it works, but I do know at least that much. I agree with charging them to 360v, it's a good idea.

ThinkDesignConstruct (author)  dudes2 years ago

we match eachother with knowledge XD

2 years ago

Haha it does seem so. Well, let me know when you make the coilgun.

dudes2 years ago

Define 'decently fast'. Do you mean a few seconds, a few minutes, etc?

ThinkDesignConstruct (author)  dudes2 years ago

like 15-30 seconds

2 years ago

Alright, well I you want to charge them all at the same time with one circuit, you would need something that puts out 400 volts at 4 amps (15 second charge). That's 1600 watts! A little more reasonably would be charging them in sets of three, which would require at least 400v at 800mA (15 seconds). 30 seconds would be safer and easier, actually the longer, the easier. Where, if I may ask, did you get ahold of such powerful caps? And were they reasonably priced?

ThinkDesignConstruct (author)  dudes2 years ago

So for 30 sec charge per stage would require 400v @400ma?

2 years ago

also most likely I would ant to charge it to 360v because of surges ect so it doesn't fry the caps

ThinkDesignConstruct (author)  dudes2 years ago

I agree with the sets of sets of 3 idea that's my original design I would need 5 circuits though and here is the link to my caps good sir http://parts.arrow.com/item/detail/cornell-dubilier-electronics/dcmce1671#8uu3

2 years ago