Electromagnetic Coil Launcher Project
or aluminum and add support pieces
of one inch square aluminum tube.
Solder a length of two-strand wire to
the common and normally open
contacts on the microswitch. If you
use a momentary contact switch,
make sure that it is normally open.
Another alternative is to cut the
pistol grip and trigger from one of
the many inexpensive toys that are
available on the market and rewire the
switch. The completed grip with fire
switch is shown in Figure 12.
■ FIGURE 10. Accelerator
coil, barrel, and breech
Fabricating the Stock
and Side Panels
The stock for the EM- 15 was fabricated with 1/2 inch aluminum angle and
1/16 inch thick flat stock but you can use
whatever material you have access to. A
metal bender was used to shape the
pieces and all holes were made with a
drill press. The side panels and covers are
shown in Figure 13. The capacitor bank,
side panels, and trigger assembly are
shown in Figure 14. A closer view of the
adjustable breech mounted to the rest of
the launcher is shown in Figure 15.
■ FIGURE 11. Pistol grip cutting guide.
Calibrating the Gun
I suggest setting up all of the electronic components on your workbench to calibrate the launcher before
assembling all of the parts into the
stock. Connect the 12 volt battery
pack, fire switch, accelerator coil, and
capacitor bank to the circuit board. Be
very careful not to touch the circuit
board or any of the connections while
testing the device. If you need to
rewire or make an adjustment, then
disconnect the battery pack and be
sure to short out the capacitor bank.
Set your multimeter to measure
DC and then clip the leads to the
capacitor bank terminals. Place a fresh
set of batteries into the battery holder
and turn the voltage potentiometer
R11 all the way counter-clockwise and
then turn on the main power switch.
The ‘power’ and ‘charge’ LEDs should
turn on. You will see the voltage rise
to approximately 350 volts DC at
which time the ‘fire’ LED turns on and
the charging action will stop.
Mark 350V on the control panel
at that position with a pencil or marker. Slowly turn the potentiometer
clockwise until the voltage is 400
VDC and make another mark on the
panel there. Continue this procedure
in increments of 50 volts until you
reach 800 VDC, marking each position of the potentiometer on the panel
face with a pencil or marker as you go.
Be sure not to charge the capacitor
FOR YOUR INFO
The concept of electromagnetic launchers has actually
been around for a while. The June 1932 Modern
Mechanics magazine cover story featured an electric
cannon built by an English
designer named Dr. Kapitza.
The story reported that the
firing of shells was accomplished by shortcircuiting
powerful dynamos for periods of 1/100th of a second.
This approach sounds
very similar to the modern
compensated pulsed alternators (compulsators) being used to power the rail guns
being developed at the University of Texas at Austin for
the US Army electric gun program. For more information
about the research going on at the University of Texas,
visit their website at www.utexas.edu/research/cem/
March 2008 55