Remembering Jack Kilby, Father of the Integrated Circuit

Editor,

I was very glad to see your article about Jack Kilby in The Citizen Scientist ("Jack Kilby, Inventor of the Integrated Circuit, 1923 -2005," TCS, 26 August 2005). I have followed his life very closely, and I'd like someday to get out to Great Bend, Kansas, and walk around where he grew up and first learned to love electronics.

For the longest time I was looking for the schematic for Jack Kilby's first prototype integrated circuit, never really able to sift through all the literature that featured mostly his physical sketches. It turns out the schematic can be found by zooming into the Kilby Awards emblem, which is a very interesting parallel to the way one would have to look at the actual prototype.

I think the transistor was a PNP, with the emitter tied to "+V," but I'm not sure. What do you think?

Mark Valentine

The circuit you mention is reproduced nearby as Fig. 1. As you suggest, the transistor is probably a PNP device with the emitter tied to +V and the collector to V- through R1. The circuit appears to be an oscillator, and this is confirmed by a Texas Instruments web site: "Kilby began to write down and sketch out his ideas in July of 1958. By September, he was ready to demonstrate a working integrated circuit built on a piece of semiconductor material. Several executives, including former TI Chairman Mark Shepherd, gathered for the event on September 12, 1958. What they saw was a sliver of germanium, with protruding wires, glued to a glass slide. It was a rough device, but when Kilby pressed the switch, an unending sine curve undulated across the oscilloscope screen. His invention worked — he had solved the problem."

Editor

More About Making Calcium Oxide and Calcium Hydroxide

Editor,

I particularly enjoyed Christian Thorstein's article on "Making Calcium Oxide and Calcium Hydroxide" (The Citizen Scientist, 26 August 2005) as lime burning was once the principal industry in my home town of Rockland, Maine. This flourished throughout the 19th century and midway through the 20th, but died out when the use of burnt lime for masonry mortar and wall plaster was superceded by Portland cement and dry wall, respectively. I'm old enough to remember horse-drawn, two-wheeled drays conveying limestone from the quarries to the waterfront kilns.

I would recommend the white marble chips available from the garden section of your local big box store as a rather pure form of calcite for the experiments in Christian's article. Marble is a metamorphic form of limestone. It is formed when the stone is subjected to heat and pressure in the course of its geological history.

Iceland spar is a transparent, rhombohedral form of calcite that exhibits the phenomenon of double refraction. When a  beam of unpolarized light strikes a rhomb of spar at an acute angle, it splits into right- and left-polarized beams. If you look through a crystal of spar placed over a line of print, two lines will be seen. Nicoll prisms, which are used as polarizers in polarimeters, are made by cementing two wedges of spar together is such a way that the emergent beam is polarized. Large perfect crystals of spar are somewhat rare as they easily fracture into smaller rhombs.

In my youth I enjoyed mineralogical rambles (and skinny dips!) in the local abandoned quarries and was lucky enough to find some nice clear, though small, pieces of Iceland spar. Larger crystals, however, showed interior fracture planes and would fall apart into smaller rhombs when struck lightly with a hammer.

As another demonstration of the exothermic reaction of CaO with water, I once tried calcining a small rhomb of my Iceland spar. On cooling the crystal retained its rhombic shape, but on allowing a drop of water to fall on it a puff of steam resulted and the crystal crumbled into a mass of Ca(OH)₂.

Norm Stanley

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