One of the most essential parts of this project is the high voltage supply. There are to ways to do this. One is to buy a 12 florescent light. Pull this apart and you will have a very compact and efficient power supply capable of 500volts or so. Another option is to use a ccfl inverter. These inverters are used to power in car neons and the like. This nifty little power supply is capable of supplying several thousand volts with a fair amount of current. You can even use it to draw electric arcs a few mm across. Here's a picture of a ccfl inverter.
To charge the capacitor, a DC (direct current) source is needed, these inverters supply an AC source. To change this we need to use a rectifier which will consist of 4 diodes. I used the cheap, readily available 1n4007's available at you electronics store.
The final major components are the high voltage capacitor, a suitable switching device, and the coil/barrel arrangement. Ideally, the capacitor needs to be as large as possible with the highest possible voltage rating. However, you then need a switching device that can handle the high currents and voltages involved. There is also the added danger of electrocution, etc. Another factor that comes into play when choosing a suitable capacitor is the ESR (equivalent series resistance), however, to reduce the cost of buying the capacitor this factor will be ignored. For this project i chose a 100uf, 450vdc electrolytic capacitor. I brought this for $10 from my local electronics store. The capacitor is big enough to power the coil gun, yet small and relatively safe enough to use provided precautions are taken. The capacitor is also small enough that a readily available SCR ( silicon controlled rectifier) can be used as a switch. If you don't know what this is or how it works, Wikipedia is your friend! Put simply, an SCR is just an electronic switch. You apply a voltage to it and the switch closes. Below are some pictures of everything you need for the coil gun, minus the 12 power supply and coil/barrel. I will give explanation of these and how to put together the coil gun in my next post. I will also post some videos of the coil gun in action in the coming week. This week is exam week and so won't have time for testing.
Sorry about the picture quality, I'm using my laptop webcam as a camera. I will soon get a half decent digital camera and will take some better pictures.
Cheers, chris
