Each module contains a high voltage charger, an optical trigger, capacitor bank, voltage indicator, accelerator coil and switch circuitry. When the projectile interrupts an infrared beam at one end, it triggers a pulse of several hundred amps through the acceleration coil. The pulse peaks after approximately 4 ms. The projectile is then accelerated through the module.

This is a modular design that uses optical triggers. Because of this, it is possible to stack several modules to achieve more power (each module weighs approx 1 Kg)

If you want to see the this thing in action, there is a video on YouTube: youtube.com/watch?v=KeSjeUIltcI, and on my blog: timeexpander.com/wordpress/archives/5124 (norwegian only - sorry)

Please be _very_ careful if you plan on building something like this. I am myself an amateur regarding electronics and I can make no promises or guarantees regarding the safety of the electronics or design.

Parts list:
- thingiverse.com/thing:19687
- 12-15 V power supply / battery
- 47 ohm 0,5W resistor
- 1 kohm 0,5W resistor (2 x)
- 390 kohm 0,5W resistor
- 4 kohm 0,5W resistor
- 450V/1000uF capacitors (6 x. Maximum dimensions are 35 x 65 mm)
- LED Bargraph display
- LM3914
- 7805 Voltage regulator
- TSAL7200 (or equivalent) IR diode
- LTR3208E (or equivalent) phototransistor
- 2N3904 small signal transistor (or equivalent)
- 50RIA120 SCR (or equivalent). Must be able to survive a current of 7-800 A for the pulse duration (typically 8-10 ms)
- 47 ohm (5W or higher) current limiting resistor (to be mounted between the boost converter and capacitor bank)
- 450V capable switch with a 300 ohm/5W minimum current limiting resistor (to be mounted across the capacitors as a safety discharge switch. This is essential in case of a misfire. The capacitors can store a lethal charge for more than a day). The design accommodates a switch with a form factor like an arcade microswitch.
- carbon fiber tube (5 mm outer diameter). Use a dremel tool to create slots for the infrared light beam.
- approx 150 grams of 1mm insulated copper wire for the accelleration
coil. The coil should have a series resistance of approx 0,3-0,4 ohm and an inductance of approx 190 uH (You can counterwind parts of the coil to reduce inductance if you need a higher series resistance). With these parameters the pulse should be critically damped and there will (hopefully) not be a need for additional protection circuitry.
- plastite screws (12)

(The two additional schematics you will need are in the video)

PS. varying the length of the projectile can make a really big difference in kinetic energy.