How can i charge a 400v 3900 uf capacitor for a coil gun (w/o killing my cap)?
You can build a simple voltage doubler from a 120 vac outlet that will charge it in seconds. 120 volts with a single diode will give you 165 volts DC. A doubler will give you 330 volts DC. I’d avoid the tripler, as that will produce 500 volts and will destroy a 400 volt cap. Be very careful! These are lethal voltages that will kill you in a second. The charge on the cap will also kill you easily. Some schematics at http://www.tpub.com/neets/book7/27m.htm Put a small resistor in series with the large cap when you charge it to prevent high inrush currents that could damage it. 400 ohms 5 watts should do. The time constant is 400*.004 or 1.6 seconds, which means it will charge up in 5 seconds.
