Picture Gallery
In mid-May 2003 I reconstructed my coilgun for a poster
demonstration at Cal State Northridge. Afterwards I took pictures with
my father's camera, and now they're finally online.
This is the new setup: the interesting stuff is on
top, and the dangerous, messy, or boring stuff is underneath. The box is made
of a cardboard sheet and a cat litter box. I had my brother test the voltage
while I took a picture; the image is modified to better show the reading. The
rightmost picture shows a firing test - you can see the projectile emerging
from the barrel.
These are the crucial components. The left picture
is of the voltage doubling circuit, which converts the 120 VAC wall voltage
to 240 VAC. That's a peak charging voltage of 340 volts. The center picture
shows the charging circuit: a resistor to limit the charging current, a neon
lamp that lights when the capacitor reaches a certain voltage (notice that
it's on), and more resistors to slowly bleed the capacitor in case it is left
charged. On the right is the main coil - 40mm x 25mm.
The styrofoam and popsicle stick construction on the
left catches the projectile. Underneath the cardboard top, the guts of the
coilgun are mostly disorganized. Not wanting to do a lot of wiring and soldering,
I used alligator clips to connect various components. When the coilgun fires, the
Lorentz force (the same force that propels a railgun projectile) causes all the
loose wires to jump, some hitting the cardboard with a snap. On the right you
see the maximum charge of the capacitor (which can vary from outlet to outlet).
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