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Coilgun capacitor charging circuit questions

  1. Jan 23, 2016 #1
    I've been making coil guns out of a disposable camera's flash circuit recently, and when experimenting with the capacitors themselves I've come across some things I can't explain, so I hope someone else can.

    1. SOLVED: My mistake (In order to make my experiments easier, in place of the capacitor, I soldered a female power jack, and then I soldered the capacitor to a male power jack. I checked the polarity and its all good. I also soldered four other capacitors in parallel to another male power jack. For some reason, maybe because the wires connecting the capacitors are too long or something, neither of the capacitors charge. The light on the circuit comes on immediately when the charging switch it turned on, with no noise coming from the capacitor. And to add to that, the coil doesn't fire. But with both the single capacitor, and the 4 capacitors, I've tried connecting them directly to the circuit, and the whole thing works normally)

    2. When connecting them directly to the circuit, the single capacitor charges to 346v, like it should, but the four capacitors only charge to about 5v. Why is this? Shouldn't capacitors in parallel just have a larger capacitance together? I've seen other people put capacitors in parallel so that they can provide more current for a stronger electromagnet, but for me its never worked.

    3. Lastly, when people have multiple capacitors in parallel, do they do that because the multiple capacitors innately create a stronger coilgun, or is it because it has to be coupled with a coil with less resistance that draws more current, which the multiple capacitors are able to supply?
    Last edited: Jan 23, 2016
  2. jcsd
  3. Jan 23, 2016 #2
    Send the data on the capacitors.

    I seem to recall some camera capacitors are "smart". They have control circuitry.

    On point 3, yes. Multiple capacitors make for a stronger gun. They do this in part by lowering the "resistance" (Actually the capacitive reactance which is proportional to 1/C.)

    BTW, keep your velocities and currents at safe levels while playing. Lots of bad things can happen when electricity is abused.
  4. Jan 23, 2016 #3
    Yes, I'm trying to stay safe. Thanks for the warning. Thats good to know that it is the impedance of the capacitors themselves that gets reduced, so I don't necessarily need a different coil as well. Anyways, I fell really dumb about question one, as I just was doing some troubleshooting, and realized I messed up the connections on the power jack, so I'll edit that now.

    The capacitors for the 4 parallel assembly are 330v 135 μF photo flash capacitors, and thats really all I can say just from looking at em. I bought them from http://www.ebay.com/itm/281375909960?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT Just one of them works normally, as far as I can see.
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