This is a plasma globe that I made out of parts that I found lying around the shed and house. The man parts are the ignition coil, large light globe, capacitor and the light dimmer. Once assembled this is not something that you would want to touch, unlike the plasma globes that you can buy from places such as K-Mart or an electronics store, which put out minimal current.
The light dimmer I used is an important part of making this work as it regulates the amount of current that the plasma globe puts out. The Capacitor seems to act like a sort of resistor when used in this configuration, if it were removed from the circuit it creates a massive arc from the secondary terminal to ground on the ignition coil. Which will quickly overheat the ignition coil and light dimmer. I used a larger heat sink on the transistor that is built into the light dimmer, to prevent any overheating issues. Please see the simplified schematic below for the correct way to wire the internals.
I used some magnet wire (varnish insulated wire) from the negative terminal on the ignition coil and glued it around the top of the light globe to enhance the visual effect of the plasma. The electronic components were placed inside a scrap piece of PVC pipe and the bottom was sealed. I filled the inside with mineral oil to stop any internal arcing or shorts, and then sealed the top cap on with glue.
This unit runs off 240V mains and consumes approx 200-300 watts depending on power setting on the dimmer and the capacitance of the capacitor (the one I used was from a house hold fan, approx 1.2 uf, 500V.AC). A high resistance resistor should be added to across the terminals of the capacitor to discharge any current after shut off, which I should have done before sealing the unit as I got a small shock off the plug once I had unplugged it. I learnt to discharge the unit by shorting the plug with a screw driver or metal object. This is not recommended, do it right the first time and add the resistor!
Remember always use a high level of caution around electricity!
Project Completed: 2010