The electric/lightning globe- how does it work?

[AbsolutTalent]

anyone know what im talking about?

those orbs that you touch the globe and the red or blue electic arcs to where your hand is in contact with. You see them all the time at places like Spencers Gifts and other novelty stores


Anyways...i am looking for something or someone to explain to me how it is done and why it does what it does

thanks

 

[zsouthboy]

<- is also quite interested in how this works

I can't even remember the NAME of this thing...

 

[Fencer128]

It's called a plasma globe. Do a google on plasma globes and I'm sure you'll find the details.

Basically it's a globe filled with a mixture of inert gases. In the centre is a cathode at a large potential difference (thousands of volts). The cathode is supplied with an AC/modulated DC current that alternates many times per second.

The electricity arcs from the cathode through the gas to the wall of the globe. As the electricity moves through the noble gas it excites and ionises the atoms, causing them to emit light. A plasma is an ionised gas - so this is why its called a plasma globe. When the finger of light reaches the wall of the globe it collects any electrons necessary to de-ionise and so the plasma dissipates.

If you hold a fluorescent tube against the wall of the globe it will light up. THe EM field caused by the AC will be enough to get the gas moving in the tube. Collisions between the molecule cause emission ---> tube lighting up.

Hope that gives you a quick overview.

Cheers,

Andy

 

[Smilin]

I'm not sure I understand why the glass acts as a ground / anode.

hehe btw I have one of these things on top of my computer that looks like electric mushrooms growing out of it. It's been up there for a year now - hell I figured the computer wouldn't boot from all the EM, go figure.

 

[CTho9305]

I would guess you get a capacitor-like effect across the glass. But that doesn't exactly work out, because it would charge, and then the lightning would stop following your finger.

 

[f95toli]

When you touch the glass you "ground" it a litte bit, some charge goes through your body to ground, that is why the "lighting" is "attracted" by your hand.

 

[Mark R]

The power produced by the central electrode is high-frequency AC - essentially radio signals.

The power is attracted to your finger because of the increased capacitance in produces. Because the power is AC, the capcitance repeatedly charges and discharges, so the current continues to flow.

 

[AbsolutTalent]

ok...then this brings me to my next set of questions about this..


would it be easy to create one of these at home? And does it have to be made into a globe shape?

And putting this close to any comptuer components will cuase them to not work?


I had a computer mod idea reguarding this. Makeing a case (or one side) out of glass with this in it. I thought it would be a neat idea that no ones seen before

 

[Amorphus]

some guy on bit-tech did that, actually. poor you, you thought you had an original idea, too. macroman or linear put one in the front bezel of his case.

also, it wouldn't be all that easy to make, but you probably could. no, it does not have to be in a globe shape. I've seen them in the shape of dolphins, and swirly shapes, at novelty stores. and the EMI would not affect anything other than monitors, so I am led to believe (correct me if I'm wrong, some of you smart people, eh?)

 

[PowerMacG5]

The Screen Savers on TechTV did something like this. Basically, you use a plasma generator. Here is the link.

 

[Mark R]

Nothing to stop you building your own - you just need to know about high-voltage, radio frequency electronics.

The globe contains low-pressure gas, which glows gently under a low voltage (only a few hundred volts). If you didn't enclose the system it would have to operate through air with consequently much higher voltage (hundreds of thousands of volts).

Anyway, here are some home-made attempts (not mine, I wouldn't go near those things). Link