Category Archives: Inventions

 As a result of a trip to the U.S.A. in June 1946, Dr F.C. (Freddie) Williams started active investigation at TRE into the storage of both analog and digital information on a Cathode Ray Tube. Storage of analog information could help solve the problem of static objects cluttering the dynamic picture on a radar screen (because). Storage of digital information could solve the problem holding up the development of computers worldwide, i.e. lack of a storage mechanism that would work at electronic speeds. By November 1946 he was able to store a single bit (with the “anticipation” method), based around a standard radar CRT, and filed a provisional patent for the mechanism in December 1946.

The general principle behind the storage of binary information was to plant charge in one of two different ways at an array of spots on a CRT using standard techniques. The type of charge at any spot, representing a 0 or 1, could be sensed by a metal pick-up plate on the outside of the CRT screen, thus “reading” the “value” of the spot. However, the charge dissipated very quickly, so values were preserved indefinitely by continuously reading their value and resetting the charge as appropriate to the value.

A bit (abbreviated b) is the most basic information unit used in computing and information theory. A single bit (short for binary digit) is a zero or a one, or a true or a false, or for that matter any two mutually exclusive states. Claude E. Shannon first used the word bit in a 1948 paper.

Back in 1904, British scientist John Ambrose Fleming first showed his device to convert an alternating current signal into direct current. The “Fleming diode” was based on an effect that Thomas Edison had first discovered in 1880, and had not put to useful work at the time. This diode essentially consisted of an incandescent light bulb with an extra electrode inside. When the bulb’s filament is heated white-hot, electrons are boiled off its surface and into the vacuum inside the bulb. If the extra electrode (also called an “plate” or “anode”) is made more positive than the hot filament, a direct current flows through the vacuum. And since the extra electrode is cold and the filament is hot, this current can only flow from the filament to the electrode, not the other way. So, AC signals can be converted into DC. Fleming’s diode was first used as a sensitive detector of the weak signals produced by the new wireless telegraph. Later (and to this day), the diode vacuum tube was used to convert AC into DC in power supplies for electronic equipment.

Pioneered with the advent of the first transistor using semiconductor materials at Bell Labs by John Bardeen and Walter Brattain, semiconductors have had a monumental impact on our society. You find them at the heart of microprocessor chips as well as transistors. Anything that’s computerized or uses radio waves depends on semiconductors. Today, most semiconductor chips and transistors are created with silicon. You may have heard expressions like “Silicon Valley” and the “silicon economy,” and that’s why — silicon is the heart of any electronic device.

The first transistor was about half an inch high. That’s mammoth by today’s standards, when 7 million transistors can fit on a single computer chip. It was nevertheless an amazing piece of technology. It was built by Walter Brattain.

Before Brattain started, John Bardeen told him that they would need two metal contacts within .002 inches of each other — about the thickness of a sheet of paper. But the finest wires then were almost three times that width and couldn’t provide the kind of precision they needed. Instead of bothering with tiny wires, Brattain attached a single strip of gold foil over the point of a plastic triangle. With a razor blade, he sliced through the gold right at the tip of the triangle. Voila: two gold contacts just a hair-width apart.

The whole triangle was then held over a crystal of germanium on a spring, so that the contacts lightly touched the surface. The germanium itself sat on a metal plate attached to a voltage source. This contraption was the very first semiconductor amplifier, because when a bit of current came through one of the gold contacts, another even stronger current came out the other contact.

Here’s why it worked: Germanium is a semiconductor and, if properly treated, can either let lots of current through or let none through. This germanium had an excess of electrons, but when an electric signal traveled in through the gold foil, it injected holes (the opposite of electrons) into the surface. This created a thin layer along the top of the germanium with too few electrons.

This device was made using paper clips and razor blades, and was first used in an audio amplifier to present to Bell executives.