My first attempt at a coilgun was when I was only 14 years old. In those days I didn't have access to Internet,
and my access to good reading material was spotty at best. Still, I got it working and it was among the first
projects that I dreamt up to actually get working. Of course when I look back on it, such a device
seems trivial. But to a 14-year old it seemed pretty awesome!
Although I didn't have very many resources, I managed to find a good length of wire and wrap a small coil around a short
length of thin copper tubing. My battery pack was a 12-volt gel-cell which was, at the time, my primary DC power source.
Although I never actually got it to fire a projectile at any decent velocities, it did succeed in pushing the screwdriver
bit from the end of the barrel, proving my theory that it would work.
Recently, I was thinking about that experiment I did so many years ago and decided to try again. I looked around the Internet
and behold, there was a whole heap of people playing with these things! First of all, I needed a coil - and do I ever hate winding
coils! Putting my loathing of coil-winding aside I built an improvised winding rig out of a drill and some various pieces of
hardware which happened to be nearby. I wound it directly on it's final form, a piece of plastic tubing from a pen which
had been trimmed to a good length then swabbed liberally with Isopropyl Alcohol on the inside to remove the sticky stuff.
I managed to wind a decent coil and attached it to an improvised trigatron built from an old disposable camera flash unit.
The coil is about five layers of about a meter each, 30ga laquer insulated wire. The improvised trigatron is an important
design aspect - when the Xenon tube ionizes, it permits the current to flow through the coil, saving any mechanical switches
from meltdown. The capacitor bank is comprised of six 160uF photoflash capacitors wired in parallel. I tried a bank of twelve
capacitors to start with, but I could never get them all to charge with the fairly wimpy camera charger (for this version I
just used the camera's flash circuit to charge the capacitor bank to simplify things).
After hooking everything up, I made some slugs from 3/16" steel. The first attempt launched a slug across the table - far
exceeding my expectations! After a few attempts (and removing half the capacitors), I was able to charge the bank up to
approximately 290 volts, and repeatedly fired the projectile across the room. I did some experimenting with various slugs,
and made some from nails of various sizes. The larger diameter slugs worked best, the largest being accelerated with enough
force to stick them through a paper target.
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