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# 12kj coilgun help

I have 15 10000 uf 400v 17200 ma capacitors I was wondering what the best way to charge them would be each stage will be ran from 3 caps making 2400j each stage for 5 stages. If there is no efficient way to charge all at once I would like to be able to charge each stage separately.

## Comments

Best Answer 6 years ago

I would get a mains to 440vac 1kva standard control transformer some where near your main city to save cost of shipping, connect a 50 amp DC bridge ...... aw here is the circuit. Don't worry about exceeding the transformer current rating on the first few charges because the rate decreases as the cap voltage increases.

Use a voltmeter to stop charging at 400V or fire the cannon.

Answer 6 years ago

thank you i was hoping to charge it off a dc input no ac i will change it later in testing also for the coil how many turns and layers would give me the most efficiency

Answer 6 years ago

You need to decide on your slug mass, diameter and length.

After that decide what exit velocity want and you can figure the force you need over the barrel distance

http://en.wikipedia.org/wiki/Force

Next you create a coil design that gives the force you need

https://www.easycalculation.com/engineering/electr...

BTW a Force of 10 Newtons is 2.248 pounds.

Finally you examine the inductance for calculating the timing release of your stored energy to propel your slug

http://www.66pacific.com/calculators/coil_calc.asp...

6 years ago

I don't know of any 400 volt, 10 mF condensers ie capacitors with a

17 amprating.Answer 6 years ago

(sigh) http://parts.arrow.com/item/detail/cornell-dubilier-electronics/dcmce1671#8uu3

Answer 6 years ago

OK it, the cap a manufactured by Cornell Dublier 10,000uF = 10mF at 400 VDC and ability to handle an AC ripple current up to 17.2 amps for $55...

Yes, three in parallel can hold 2400 joules.

So any charging scheme will work.

Do your groups share a common ground /

Answer 6 years ago

i would like to refer you to my forum topic about the same thing only a little more answered also how would you get a 400v 400ma output from a dc power source of course you dont want to plug it into an outlet between each shot

Answer 6 years ago

here is link. To my forum topic

Answer 6 years ago

Here it is https://www.instructables.com/community/12kj-coilgun-project/

Answer 6 years ago

yes they all have a common ground they are to be lined up in parallel.

Answer 6 years ago

i just dont know of any 400v 400ma dc-dc converter outputs