Isegoria

The flip-flop was created 100 years ago — in the pre-digital age:

Many engineers are familiar with the names of Lee de Forest, who invented the amplifying vacuum tube, or John Bardeen, Walter Brattain, and William Shockley, who invented the transistor. Yet few know the names of William Eccles and F.W. Jordan, who applied for a patent for the flip-flop 100 years ago, in June 1918. The flip-flop is a crucial building block of digital circuits: It acts as an electronic toggle switch that can be set to stay on or off even after an initial electrical control signal has ceased. This allows circuits to remember and synchronize their states, and thus allows them to perform sequential logic.

The flip-flop was created in the predigital age as a trigger relay for radio designs. Its existence was popularized by an article in the December 1919 issue of The Radio Review [PDF], and two decades later, the flip-flop would find its way into the Colossus computer [PDF], used in England to break German wartime ciphers, and into the ENIAC in the United States.

Modern flip-flops are built in countless numbers out of transistors in integrated circuits, but, as the centenary of the flip-flop approached, I decided to replicate Eccles and Jordan’s original circuit as closely as possible.

This circuit is built around two vacuum tubes, so I started there. Originally, Eccles and Jordan most likely used Audion tubes or British-made knock-offs. The Audion was invented by de Forest, and it was the first vacuum tube to demonstrate amplification, allowing a weak signal applied to a grid to control a much larger electrical current flowing from a filament to a plate. But these early tubes were handmade and unreliable, and it would be impractical to obtain a usable pair today.

Instead I turned to the UX201A, an improved variant of the UV201 tube that General Electric started producing in 1920. While still close in time to the original patent, the UV201 marked the beginning of vacuum-tube mass production, and a consequent leap in reliability and availability. I was able to purchase two 01A tubes for about US $35 apiece.

In a flip-flop, the tubes are cross-coupled in a careful balancing act, using pairs of resistors to control voltages. This balancing act means that turning off one tube, even momentarily, turns the second tube on and keeps the first tube off. This state of affairs continues until the second tube is turned off with a control signal, which pushes the first tube on and keeps the second tube off.

Achieving the right balance means getting the values of the resistors just right. In their laboratory, Eccles and Jordan would have used resistor decade boxes, bulky pieces of equipment that would have let them dial in resistances at different points in their circuit. For reasons of space, I decided to use fixed resistors of a similar vintage as the patent.

I was able to obtain a set of such resistors from the collection of antique radios that I’ve accumulated over the years. In the 1920s, radio manufacturing exploded, and the result is that I have quite a few early radios that are pretty nondescript and beyond repair, so I didn’t feel too bad about cannibalizing them for parts. Resistors made before 1925 were generally placed into sockets, rather than soldered into a circuit board, so extracting them wasn’t hard.

The hard part was that these resistors are very imprecise. They were handmade with a resistive carbon element held between clips in a glass enclosure. One way to get their resistance closer to the desired value is to open up the enclosure, remove the strip of carbon, make notches in it to increase its resistance, and put it back in. I adjusted several of the resistors this way, but it was too tricky to do with others, so for those I cheated a little and placed modern resistors inside the vintage glass casing.

I used modern battery supplies, in order to avoid the use of the numerous wet cells that the inventors probably used. One of the issues with tube-based circuits is that a range of voltages is required. Four D cells wired in series provides the 6 volts needed for the indicator lamps and the filament of the tubes. Connecting eleven 9-V batteries in series provided the 99 V required for the tubes’ plate. A similarly constructed 63-V power supply is needed to negatively bias the tubes’ grids. Old-fashioned brass doorbell buttons let me tap a 9-V battery connection to provide the control pulses. To show the flip-flop’s state, I used sensitive antique telegraph relays that operate miniature incandescent lamps.

With a lot of trial and error and tweaking of my nearly century-old components, over the course of a year I was finally able to achieve stable operation of this venerable circuit!

Kitty Hawk Corporation’s new Cora air taxi “is powered by 12 independent lift fans, which enable her to take off and land vertically like a helicopter” and has a range of “about 62 miles” while flying at “about 110 miles per hour” at an altitude “between 500 ft to 3000 ft above the ground”:

Researchers from RMIT University in Melbourne, Australia have produced a working-prototype proton battery, which combines the best aspects of hydrogen fuel cells and battery-based electrical power:

The latest version combines a carbon electrode for solid-state storage of hydrogen with a reversible fuel cell to provide an integrated rechargeable unit.

The successful use of an electrode made from activated carbon in a proton battery is a significant step forward and is reported in the International Journal of Hydrogen Energy.

During charging, protons produced by water splitting in a reversible fuel cell are conducted through the cell membrane and directly bond with the storage material with the aid of electrons supplied by the applied voltage, without forming hydrogen gas.

In electricity supply mode this process is reversed; hydrogen atoms are released from the storage and lose an electron to become protons once again. These protons then pass back through the cell membrane where they combine with oxygen and electrons from the external circuit to re-form water.

A major potential advantage of the proton battery is much higher energy efficiency than conventional hydrogen systems, making it comparable to lithium ion batteries. The losses associated with hydrogen gas evolution and splitting back into protons are eliminated.

Several years ago the RMIT team showed that a proton battery with a metal alloy electrode for storing hydrogen could work, but its reversibility and rechargeability was too low. Also the alloy employed contained rare-earth elements, and was thus heavy and costly.

The latest experimental results showed that a porous activated-carbon electrode made from phenolic resin was able to store around 1 wt% hydrogen in the electrode. This is an energy per unit mass already comparable with commercially-available lithium ion batteries, even though the proton battery is far from being optimised. The maximum cell voltage was 1.2 volt.

Back in the “Atoms for Peace” era, the US’s Project Plowshare attempted to harness peaceful nuclear explosions for massive public works. The first test, Project Gnome, took place roughly 40 km (25 mi) southeast of Carlsbad, New Mexico, in an area of salt and potash mines along with oil and gas wells:

It was learned during the 1957 Plumbbob-Rainier tests that an underground nuclear detonation created large quantities of heat as well as radioisotopes, but most would quickly become trapped in the molten rock and become unusable as the rock resolidifed. For this reason, it was decided that Gnome would be detonated in bedded rock salt. The plan was to then pipe water through the molten salt and use the generated steam to produce electricity. The hardened salt could be subsequently dissolved in water in order to extract the radioisotopes. Gnome was considered extremely important to the future of nuclear science because it could show that nuclear weapons might be used in peaceful applications. The Atomic Energy Commission invited representatives from various nations, the U.N., the media, interested scientists and some Carlsbad residents.

“We’re going to set off an atomic bomb in a cave. You wanna come?”

Gnome was placed 361 m (1,184 ft) underground at the end of a 340 m (1,115 ft) tunnel that was supposed to be self-sealing upon detonation. Gnome was detonated on 10 December 1961, with a yield of 3.1 kilotons. Even though the Gnome shot was supposed to seal itself, the plan did not quite work. Two to three minutes after detonation, smoke and steam began to rise from the shaft. Consequently, some radiation was released and detected off site, but it quickly decayed.

The cavity volume was calculated to be 28,000 ± 2,800 cubic meters with an average radius of 17.4 m in the lower portion measured. The Gnome detonation created a cavity about 170 ft (52 m) wide and almost 90 ft (27 m) high with a floor of melted rock and salt. A new shaft was drilled near the original and, on 17 May 1962, crews entered the Gnome Cavity. Even though almost six months had passed since the detonation, the temperature inside the cavity was still around 140 °F (60 °C). Inside, they found stalactites made of melted salt, as well as the walls of the cavity covered in salt. The intense radiation of the detonation colored the salt multiple shades of blue, green, and violet. Nonetheless, the explorers encountered only 5 milliroentgen, and it was considered safe for them to enter the cavern and cross its central rubble pile. While the three-kiloton explosion had melted 2400 tons of salt, the explosion had caused the collapse of the sides and top of the chamber, adding 28,000 tons of rubble that mixed with the molten salt and rapidly reduced its temperature. This was the reason the drilling program had originally been unsuccessful, finding temperatures of only 200 F, without high pressure steam, though the boreholes had encountered occasional pockets of molten salt at up to 1450 F deeper amid the rubble.

Today, all that exists on the surface to show what occurred below is a small concrete monument with two weathered and slightly vandalized plaques.

Other proposals under Project Plowshare included widening the Panama Canal, constructing a new sea-level waterway through Nicaragua nicknamed the Pan-Atomic Canal, cutting paths through mountainous areas for highways, and connecting inland river systems.

No mention of draining the Mediterranean though.

(Hat tip to commenter Sam J.)

HB11 Energy proposes an alternative to “old fashioned” deuterium-tritium fusion, laser hydrogen-boron fusion:

A scientific paper accepted for publication describes the road map that has deemed the approach by one of the founders with his team as a viable approach based on the experimentally confirmed reaction gains one billion times higher than the classical values, placing it far ahead any DT fusion approaches.

Other advantages: Unlike deuterium-tritium fusion and fission techniques, the HB11 reaction is sufficiently clean with respect to production of any harmful byproducts or radiation. It also has the potential to create electricity directly without the need for a heat exchanger and steam turbine to generate electricity as required for coal or fission nuclear power stations. This will allow power stations to be built with a relatively small capital investment and footprint based on presently achieved extreme laser technology.

We expect to be able to provide energy for about one-quarter of the price of coal fired power, without any carbon emissions or radioactive by-products, which will be disruptive to the power industry. With the small size and footprint of a HB11 power station, the addressable market is expected to reach further than the power grid to applications such as ships, submarines, large factories or to remote locations such as isolated towns and mine sites.