This is the gun part, it is constructed from 16 gauge (I think) enamelled copper wire, I was originally planning on wrapping the wire around the plastic tube like the previous one but after taking it of the role and seeing how stiff it was I mounted the roles around the coil. This isn't the best method as there is a large gap between the tube and coil and the coils aren't wound very neatly but given I had no equipment to wind them properly it was the only option.
I packed out the tube with several layers of gaffer tape so the coils made a tight fit with the tube I then carefully rested the tube and coils on a 1m length of box steel and glued where it touched with a glue gun. When this has set I wrapped gaffer tape around the coils and support to hold everything in place
Holes were then drilled through the tube just before each coil, an infrared led and photo detector were then glued in place, the first coil didn't have a light gate as I planned to trigger this coil manually.
All the wires were then run back and flexible mains cable soldered to each of the coil wires, the circuit uses a common positive terminal so I side of each of the coils were soldered together and to 2 lengths of mains cable (encase 2 coils fired together or there current was still discharging when the next coil was triggered), connect 10 pieces 16 gauge wire is very hard, a 25 watt soldering iron barely heats it up, not enough for solder I had to use a blow torch (the type used for soldering pipes) This caused some slight singing of nearby wires but it just about worked. I then attached heavy duty connector to the end of the cables and a 50 way D-type connector for the data wires (LED's and light gates) and that part was finished.
This is a very bad shot of the case (it was taken while testing), I have mounted all the electronics inside a wheel able travel case, the batteries, charger and main switches are in the base and the switching electronics are mounted on the top. This coil gun runs from 2 12v gel batteries connected in series to provide 24v, the initial plan was to connect a series of capacitors in with the batteries, these have been mounted in the case but I haven't connected them up yet.
The control electronics (light gates) runs from 5v, due to some bad resistor calculations the coil draws about 1A at 5v so the circuit I made to produce the 5v from one of the 12v batteries doesn't work, that is why you can see the bench power supply being used.
The first stage of testing was to verify that all the high current MOSFET switches worked correctly, 3 of them didn't, at some point perhaps during testing 3 of them had blown this meant that with the manual switch for the first coil not being constructed only 6 of the 10 coils were working, even though the results were still quite good, it is performing better than the previous coil gun which used 6 coils but this system runs on 24v rather than 12v so it should.
When I have time I will replace the 4 faulty MOSFET's and build a new 5v power supply, hopefully this will make things neater and improve the performance.