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A very stupid question about electricity for a project being done just for fun

  1. Dec 23, 2011 #1
    Hopefully this question hasn't been asked here before, I did a search and it seems everyone else is asking much more practical questions. Anyway...

    The Situation:

    I'm modifying a Nerf gun (this one for anyone who's curious):


    in a black and blue/electricity theme and one of the components I want to add is a small, clear, elongated dome on the top of the gun in front of the grey slider with two poles under it that, when the slider is pulled all the way back, have an arc generated between them to make it look like each dart is being charged up before being fired. The plan for how to achieve this is to put a small momentary push-button switch behind the plunger inside the gun that will be pushed when the slider pulls the plunger all the way back, connected by wire to one pole and have the other pole connected by wire to a power supply (it looks like there's enough space for one inside the handle of the gun) that's connected back to the switch. The circuit would be completed when the button is pushed and the arc jumps between the poles under the dome. I put a fairly sizable crack in the dome both for cosmetic reasons and because I know if a perfect seal were made the air inside would ionize too much after a few arcs to make any more. Obviously this whole circuit is completely useless for anything other than making a thing that does cool stuff look like it does other cool stuff it doesn't really do, but I know that even just sustaining the arc drains voltage out of the power supply so I'm working on a hatch for the butt of the gun so that the power supply can be removed and/or replaced if need be.

    The Questions (because I'm a liar like that and I thought you'd be more likely to enter the thread for one question than you would for two plus a lengthy explanation. Ha! Gotcha!):

    What kind of power supply would I need to generate the arc between the poles?

    Is there any part of this plan that you could foresee failing that I'm not seeing?

    Other (Possibly) Useful Information:

    I know the math as far as voltage/resistance/current and whatnot, but as I said before everything I've found so far has either been overly complicated or at a completely different scale than I'm working on. My main areas of interest/study are art, music, particle physics and astronomy so this is probably as complex a wiring job as I'll ever take on. I already have a very healthy respect for the power of electricity so I'm taking every precaution I can think of but if I'm missing anything, please let me know.

    Any help with this would be appreciated but either way, thanks for your time.


    P.S. I've been taking pictures and notes all throughout the process of modifying the gun so if anyone here is interested, when it's done I'll be able to post anything from just a picture or video (I'm planning on filming a short video of its "electrical capabilities" enhanced with some after-effects just to extend the project a bit and add in yet another tool or two that I don't work with that much) of it finished to a full report of exactly what I did to it (think of it as the idiot's version of a paper on a scientific experiment) as the whole project is going up on at least one other forum so I can easily post any or all of it here too. Let me know if any of you are interested in seeing any of that regardless of whether or not you have an answer to any of the questions posed above.
    Last edited: Dec 23, 2011
  2. jcsd
  3. Dec 23, 2011 #2


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    Staff: Mentor

    Rather than trying to retrofit lethal voltages to the device, would it suffice to create chaotic light effects using blue LEDS, perhaps accompanied by the crackling sound of high voltage arcing? I don't have in mind any particular way to make chaotic blue zigzag patterns, but others might be able to come up with ideas.
    Last edited: Dec 23, 2011
  4. Dec 23, 2011 #3
    I'd much rather either have the real deal or just think of another thing to put there instead. Is there another way to generate the arc that doesn't use a circuit that I could stick in there? I originally got the idea from someone who had pulled the igniter out of a long kitchen lighter but the purpose of their spark was to ignite gas in the air pressure chamber and make a Nerf ball fly further. I tried that and might have gotten the wrong type because it looked like his igniter had two wires coming out and mine only had one, the other wire runs down the fuel line of the lighter so I can't get at it. I did find a small post on the igniter that if I touch another wire to it will do the spark on occasion between the other ends of the wires but it's really far from reliable and it's kind of a pain so I'm reluctant to go that way.
  5. Dec 23, 2011 #4


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    Staff: Mentor

    I think you would be disappointed by the puny spark that even 20kV would create. Those sparks from a gas lighter, not very impressive are they? You wouldn't notice them in daylight except for their contrast against the black sooty background, and the flash is certainly are not going to light up a darkened room. The only way I can think that you'd get something real that would impress an onlooker is to try to arrange for stranded wire conductor to make a brushing contact, repeatedly. Something like you'd get if you brushed the end of stranded copper wire against one terminal of your car battery while the other end was connected via a lamp globe to the other terminal. This is low voltage, high current, and will give lots of light and a crackling sound. A couple of NiMH cells, paralleled by some good quality capacitors, should provide a high current pulse capability. Getting it to repeat in quick succession will need careful electronic design, on top of the mechanical design to cause that erratic brushing contact when you pull the trigger, etc.
  6. Dec 30, 2011 #5
    I'm not really looking for anything impressive, keep in mind we're talking about a Nerf gun here so I can't think of many people in my life who are really going to care about about the project itself much less whether or not it has an impressive arc in the dome. I just want the simplest way to get a small arc to jump momentarily between two points without having to get someone who knows how to wire a house to do it for me. It doesn't matter what noise it makes or how much of a room it lights up, as long as it works and I won't have to risk my life using the thing I'm happy. Thanks for your responses though, you've definitely given me some stuff to think about if I need to do this kind of thing on a larger scale at some point.

    ETA: The other thing to keep in mind with this is all the internal mechanics of the gun itself. The handle is pretty much the only empty part of the gun so anything I put in there has to basically fit there and have the wires to the poles go around all the bits inside. That would be the other reason I'm looking for the simplest solution possible.
    Last edited: Dec 30, 2011
  7. Dec 30, 2011 #6
    You might try to lift the flash circuit from a disposable camera.
  8. Dec 30, 2011 #7
    OoOoOoOoOoOoOoOo I like that idea. Thanks, I'll look into it!
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