im not sure how the forum here work but im hoping this topic is still open i had some more time to work on my coil gun project and using some basic arduino functions with a pot have it working with 2 coils so far not much power building a new set of coils to night and have a cnc made barrel stainless steel 20 inch's long .245 od .205 id with .040 thick wall and that leaves me .005 clearance on the inner wall to my steel round not sure of the type or quality of the ammo but its a drill bit for my small screw driver set seems to fire the best with weight and size..
soo my setup had some issues with over power at first using 6 caps to a single coil but i figured out how to use a relay and the arduino safely by taking the hard hitting punch out of the discharge by useing the the flash tube of the disposable camera and useing the discharge circuit thats already there i was able to hook a much smaller relay to the switch on the pcb bord discharging the caps threw the coil in to the flash tube and with a poorly made single coil lost a little bit of punch doing it this way but with only 3 caps now i got about 4 feet of distance i dont believe the camera board can handle more then 5 caps burnt a cupple out trying .... after that i moved on to completing a second matched to this one added a second poorly mad coil and relay with charging circuit adding a pot to the arduino that will manually adjust the timing between coil discharges it has been varey tricky to get the timing right due to the cap are not always deliveing the same amount of distance but it did add about 3 feet with the best i have gotten the timing