I’ve been wanting to build a coil gun for some time now, and finally got around to getting the supplies. There is nothing special about it, besides being wrist mounted. I use a disposable camera’s capacitor charging circuit to power the coil. I only use one capacitor, the one that came with the camera, so it’s not that strong of propulsion; enough to hurt when discharged on your wedding ring though…
The coil is almost an inch in length, and roughly half an inch thick. There are 7 layers of 20 gauge magnetic wire wound on a Bic pen. I plan on building another one with 30 gauge wire and a bigger capacitor bank. A piece of electrical tape is placed over one end near the coil to hold the tack nails in place.
The circuit found in the camera needed a little modding. I took the flash bulb off, along with the copper contacts. The button used to initiate the charge was not a push button; rather two pads… I point it out in the picture below. Anyway, I soldered two wire to them, and put it on a switch.
I extended the leads to the capacitor and put it on a pcb to solder the switches and to make a solid surface for insulating the circuit and mounting it to my wrist.
The last step was to find a way to mount it to my wrist. The first thing that comes to mind is an arm guard that protects against string scraps on bows. Much like the one below.
I stopped at Kmart to see if they have any… not in stock yet. Since the next store that would have them is too far away to make a trip this week, I went to a dollar store and bought some Velcro. This is a prototype and I plan on making a better one. I’d like to trigger the “fire” with a flex sensor, and a digital display of how many volts are on the cap. I also plan to use at least three caps on the next build; along with a bigger power supply.
It is insulated with electrical tape.
Version 2: This one is ready to be mounted to an arm guard. I also plan to replace the switch with an SCR trigger and flex sensors for the firing. I’ll be using an Arduino Pro Mini for the flex sensors, and LCD display for voltage across all 4 capacitors and battery life. May also include a laser pointer for a sight.