Coil Gun / Grappling Hook.

Hey Everyone! 

I am kind of an amatuer prop designer and I've recently been taken with pocket sized coil guns. My question is quite simple: I would like to know what disposable camera (brand) contains an LED indicator that flashes/turns on when the capacitor is fully charged? I've seen one such disposable camera used in this post: https://www.instructables.com/id/The-Coil-Gum/

I would love to know the exact brand or alternatives. 


I would really appreciate any and all help and would love to post the resulting product. 



Picture of Coil Gun / Grappling Hook.
Qcks3 years ago

Uhh.... are you just looking an LED?
Cause what you're describing just sounds like a basic design of a circuit that includes a capacitor.
Caps that are fully charged actually break the flow of electricity, which effectively allows a LED with proper resistors in place to automatically switch on. It's not a basic principle, but it is something that you should be aware of if you're going to be making bits and bobs.

notnowmyheadhurts (author)  Qcks3 years ago
Thanks, Qcks!

I really appreciate this but I'm a bit new to circuit building especially for this project, would you happen to know of or suggest a diagram (basic one) as to where the led should go or does that simply not matter?

U r welcome.
=T
I do not know of a schematic. There's many different circuits out there. i don't tend to memorize stuff because things can be so specific to the application that the electronic component is being used in.
I should note: Electronics are something i'm interested in, but i'm not especially good at them.

That said, on the positive connector of the capacitor, take a resistor and attach it as a side spur. The resistor should be appropriate to the LED amp rating (probably 200 milliamp), and the voltage source. after that hook the led with the longer leg attaching to the resistor, and then connect the other end to the other leg of the capacitor.

This would create a separate path for the electricity to follow once the capacitor is charged and the non-restricted path of the capacitor closes. You do need ohm's law (ohm = volts * amps ) to properly power your led.

If you want to add something that throws up a red light while the capacitor is charging, you'd need a transistor instead, in addition to the resistor.

Kiteman3 years ago

Just a thought - if you are going to launch a grappling hook with a coil gun, then the hooks and most of the shaft will have to be made from non-magnetic material.

Just the last part of the shaft, the bit sticking out the back of the coil, should be magnetic, otherwise the coil will just hold the grapple more firmly when you trigger the current.