6 stage coilgun
Green LED --Safe
Blue LED-Charging
Red LED-Ready to fire
This coilgun is controlled by and Arduino and it manages the timing sequence for firing the coils as well as manages power to the relays above the trigger. The relays connect all the capacitors in parallel when the blue "charge" led is lit, as well as connects power to the charging circuit. This way, when the relays are powered off, all the capacitors are electrically separated so they can be discharged independently, and power is removed from the charging circuit so it doesn't power up without a load on its high voltage output side.
The charger is a ZVS driver powering a rewound transformer. It has a 12 turn center tapped primary and a 250 turn secondary. The capacitors are 450V @ 1000uF each and discharge into the coils through a 50RIA120 SCR. The coil's base layer is 3cm long and is eight layers deep and is wound from 16awg magnet wire.
The 3cm long blunt projectile it shoots weighs in at 7.6g and gives the gun just over 10J of power at the muzzle.