filter caps for cg?
haulinick, Wed Apr 04 2007, 02:35AMHi. I've been shopping for some caps for my coilgun project and i found some fairly cheap 3,300uf 300v filter caps. Would those (being filter caps) be suitable for coilgun use?
Sorry if this is a dumb question. I tried a search and got nothing.
Thanks,
Re: filter caps for cg?
..., Wed Apr 04 2007, 03:12AM
They are a little big capacatance wise (will need a low inductance/resistance coil to reduce suckback) for their voltage, but in general they should work just fine
..., Wed Apr 04 2007, 03:12AM
They are a little big capacatance wise (will need a low inductance/resistance coil to reduce suckback) for their voltage, but in general they should work just fine
Re: filter caps for cg?
haulinick, Wed Apr 04 2007, 05:46AM
Thanks. I was hoping that would be the answer.
haulinick, Wed Apr 04 2007, 05:46AM
... wrote ...
They are a little big capacatance wise (will need a low inductance/resistance coil to reduce suckback) for their voltage, but in general they should work just fine
They are a little big capacatance wise (will need a low inductance/resistance coil to reduce suckback) for their voltage, but in general they should work just fine
Thanks. I was hoping that would be the answer.
Re: filter caps for cg?
Dave Marshall, Wed Apr 04 2007, 01:54PM
In general, just about any capacitor can be used for a coilgun. The type and values of the capacitor kind of dictates what approach you should take when designing it though.
Big filter capacitors like that don't like super fast rise times, or ultra high currents. They tend to have a relatively high ESR that can limit discharge current quite a bit, and contribute to substantial heating of the capacitor. The large capacitance is going to mean the discharge is going to last longer, and could cause suckback.
To minimize these problems, going for longer coils and heavier projectiles can help slow it down a bit. You get the same (or better) kinetic energy, but at a velocity that is easier to deal with given the higher time constant involved.
Dave
Dave Marshall, Wed Apr 04 2007, 01:54PM
In general, just about any capacitor can be used for a coilgun. The type and values of the capacitor kind of dictates what approach you should take when designing it though.
Big filter capacitors like that don't like super fast rise times, or ultra high currents. They tend to have a relatively high ESR that can limit discharge current quite a bit, and contribute to substantial heating of the capacitor. The large capacitance is going to mean the discharge is going to last longer, and could cause suckback.
To minimize these problems, going for longer coils and heavier projectiles can help slow it down a bit. You get the same (or better) kinetic energy, but at a velocity that is easier to deal with given the higher time constant involved.
Dave
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