Just for interest I dug up the patent info and here's some of the info extracted from it:
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SUMMARY OF THE INVENTION
[0011] Generally described, the present invention provides a soldering iron, with a graphite tip having two separate halves that are electrically isolated from one another. The tip halves are each electrically connected to the opposite sides of an electrical power source. When both halves of the tip are applied to an electrically conductive material, such as the material to be soldered, an electrical circuit between the tip halves and electrical power source is completed. The halves of the tip are constructed from material having high electrical resistivity and low thermal conductivity. Therefore, the tip can reach operating temperatures quickly. When the tip is removed from the joint, the electrical circuit is broken and the tip material quickly cools.
[0012] Because electricity is only able to flow when the two pieces of the tip are electrically connected, no separate switch is required. Furthermore, the soldering iron may be used without waiting for the tip to heat. The tip also reduces the risk of burning the operator and/or his or her surroundings because it heats up and cools down quickly. Furthermore, the tip material eliminates the risk of the tip becoming stuck in the joint. The tip material also permits higher power outputs than other known battery-operated portable soldering irons and permits over 300 joints for each full charge.
[0013] In accordance with further aspects of the present invention, in one embodiment, the soldering iron also includes a light disposed on the case to illuminate the tip and connection. The light is controlled by a separate switch and permits the tool to be used to illuminate the operator's surroundings without actually having to heat the tip. This aspect of the invention permits the operator to avoid the necessity of carrying a separate light source when working or intending to work in areas without sufficient lighting.
[0014] In accordance with other aspects of the invention, another embodiment is provided in which the tool also includes an electrical lead connected in series with the lamp, the power source, and a continuity testing probe. This aspect of the invention permits the soldering iron to test circuit continuity by applying the lead and the probe directly to a newly soldered connection, or to another part of the circuit to be tested. This aspect of the invention permits the operator to avoid the necessity of carrying a separate continuity tester to perform this function.
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Very similar to one I made in about 1959-60 using a file handle, a piece of brass tubing, some brass shimstock, two small brass screws, 4 washers, and a nut, a wooden file handle, some heavy wire, three crocodile clips, a car battery, and the carbon rod from a D cell Burgess battery. /ubbthreads/images/graemlins/smile.gif
Refined a bit from that, of course ... /ubbthreads/images/graemlins/grin.gif
Sounds like it will require a bit different technique, and like there may be appreciable tip erosion, but certainly workable. Hopefully replacement tips will be easy to come by, inexpensive, and simple to replace.
More info at:
USPTO Page.
