Carbon Button Lamp Answered
The Nikola Tesla group forum is asking for new projects, so I'm posting this as a suggestion. I would love to build it myself, but I lack the tools and money. This is my first contribution to Instructables, so please comment constructively.
Nikola Tesla invented the Carbon Button lamp as a kind of incandescent light, because Thomas Edison banned him from using his incandescent filament bulbs. Nikola later discovered that versions of it could also be used in wireless, trans-Atlantic telegraphy, and to investigate what we now call x rays. In fact, he even used the lamp (or something similar to it) to take x-ray photographs, 8 years before Wilhelm Rotgen discovered them.
For this reason, I must warn you: this device may possibly generate x rays. I am not responsible for any harm of any kind that may or may not result from re-creating this interesting device.
There are phosphors that you can buy that will absorb x rays and re-emit them as visible light. I recommend that you coat the bulb with it until you know for sure that the x rays aren't strong enough to hurt you, or if makes x rays at all. Mixing it with a phosphor made for uv light wouldn't hurt either.
Theory of Operation:
The bulb is powered by a Tesla Coil, or other source of high voltage, high frequency current, such as a driver for a plasma globe (actually, the modern plasma globe is descended from this kind of technology!)
When the power is turned on, electricity bombards the carbon button. Because carbon isn't the best conductor, this causes the button to heat and release electrons into the bulb's vacuum (the technical name for this is "thermionic emission," or the "Edison effect") . These electrons, in turn, excite the remaining air molecules and cause them to create visible light. This is strikingly similar to how fluorescent lamps work!
Supposedly, the bulb should shine 10 times brighter than an incandescent bulb.
(Note that the excitation of the air molecules, not the incandescence of the button, is actually the main source of light from the bulb.)
If anyone decides to build it, please post an instructable showing the steps and finished product. I suggest you get started by reading the patent, number 514,170. You may also want to read part of Tesla's lecture, "Experiments with Alternate Currents of High Potential and High Frequency."
To anyone who will attempt this, I wish you good luck!