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A 100th Birthday Celebration for the Flip Flop

It’s easy to get caught up in the excitement of creation as we’re building our latest widget. By the same token, it’s sometimes difficult to fully appreciate just how old some of the circuits we use are. Even the simplest of projects might make use of elements that were once a mess on some physicist’s or engineer’s lab bench, with components screwed to literal breadboards and power supplied by banks of wet-cell batteries.

One such circuit turns 100 years old in June, which is surprising because it literally is the building block of every computer. It’s the flip-flop, and while its inventors likely couldn’t have imagined what they were starting, their innovation became the basic storage system for the ones and zeros of the digital age.

The Trigger Relay

The second decade of the 20th century was a time of rapid innovation in electronics, brought about by the development of vacuum tube technology and the subsequent commercialization of radio. Where many of the earlier experiments in radio were the sole province of scientists trying to understand the mysteries of nature, this was a time of innovation to address practical needs. If the world was going to have radio, someone was going to have to invent it.

William Eccles. Source: Grace’s Guide to British Industrial History

Enter the team of William Eccles and F.W. Jordan. British physicists who both came of age with radio, Eccles and Jordan both contributed mightily to the field. Eccles was one of Guglielmo Marconi’s assistants and an early proponent of the then-untested theories of Oliver Heaviside that a layer of charged particles in the Earth’s atmosphere made long-distance radio communication possible. Eccles was the first to propose that the sun was responsible for the diurnal variations in propagation that had already been observed.

After the Great War, Eccles and Jordan collaborated on multiple projects, one of which led to what they called a “trigger relay.” While their original papers show that they recognized the utility of a circuit with two stable states, and even proposed uses for it, such as a latching relay that could be controlled by radio, it’s not exactly clear that they set out to invent what would become known as a bistable multivibrator. It is clear that they based their circuit on the previously published multivibrator circuit of French physicists Henri Abraham and Eugène Bloch. Composed of two triodes with their control grids capacitively cross-connected, the circuit produced square waves rather than the sine waves of most oscillators at the time. The resulting harmonics-rich signals were useful for calibrating radio equipment.

Flipping and Flopping

Eccles and Jordan realized that the astable multivibrator could be made to hold two discrete states if the grids of the triodes were resistively, instead of capacitively, cross-coupled. With the capacitors gone, the triodes are put into an unstable equilibrium that soon collapses into a stable state where one of the triodes conducts. The state of the circuit remains stable until it is perturbed by a control signal that causes the first triode to switch off and the second to conduct. The Eccles-Jordan circuit had been born.

The Eccles-Jordan trigger remained largely unused for the next 20 years or so. It eventually attracted the attention of scientists at Bletchley Park who were designing Colossus, the computers used to help break the Lorenz ciphers used by the Germans. After the war, Eccles-Jordan triggers, still using vacuum tubes, found their way into computers such as ENIAC and even into early electronic calculators.

The second half of the 20th century saw the basic principles of the Eccles-Jordan trigger modified and updated dramatically. Transistors replaced the triodes, various flavors (JK-, SR-, D-, and T-types) were developed, and everything was miniaturized onto integrated circuits. But no matter how small the circuit, the same basic topology of cross-connected inverting amplifiers is still at the heart of it all.

In honor of the 100th birthday of the flip-flop, [Richard Brewster] undertook a period-correct working replica of the Eccles-Jordan trigger, seen in the featured images for this article. Some concessions had to be made, of course — century-old audion tubes are hard to come by, after all, and the original wet-cell batteries and decade resistance boxes Eccles and Jordan likely used are too bulky and impractical these days. But he did manage to score recent updates of the UV201 triode that would have been available in 1920; expensive though they were, the UX201A tubes lend a period look to the breadboard circuit. He also used vintage glass-tube resistors from old radios, emptied of their original carbon elements and refilled with modern composition resistors. Antique telegraph relays serve to switch the loads. It’s a good-looking build and a suitable tribute to the staying power of the Eccles-Jordan circuit.

Reposted fromhackaday hackaday

Power Harvesting Challenge: Scavenge Some Power, Win Prizes

It’s a brand new day as the Power Harvesting Challenge begins. This is the newest part of the 2018 Hackaday Prize and we’re looking for 20 entries who will each receive $1,000 and move onto the finals to compete for the top five spots, scoring cash prizes of $50k, $25k, $15k, $10k, and $5k.

Put simply, Power Harvesting is anything you can do that will pull some of the energy you need from a source other than wall-power or traditional battery tech. The most obvious power harvesting technologies are solar and wind. Ditch the battery in your doorbell for a solar panel, or turn your time-lapse camera rig into one that tops its battery with a tiny wind turbine. On the other end of the spectrum you could go nuts with chemistry and develop your own take on harvesting power from saltwater, or sip off the ambient RF waves all around us.

Every Idea Matters

We live in an amazing time as chip manufacturers have squeezed every low power trick out of their silicon dies that they possibly can. The Power Harvesting Challenge is the complement to those achievements: can we now squeeze as much energy out of non-traditional sources as possible to further reduce our energy footprints?

Ideas have a way of pollinating each other and growing into something new. Explore those threads of power harvesting inspiration you come across and show them off so others may benefit. What opportunities do you see in your everyday life? Can you remove from the power grid that reading light you use for 40 minutes each night? What kind of energy would a turbine on your rain downspout generate; is it enough to power a wireless rainfall sensor indefinitely? (After all, you only need those readings when it’s raining). Turn your shoes into power plants and report back on the amount of juice you see come in for any given number of steps.

A Bit of Inspiration

Earlier this year, Hackaday’s own Sean Boyce took on a power harvesting project. He set out to build a solar-powered spot welder that charged supercapacitors using the sun’s energy. The resulting proof of concept works, and is entirely self-sufficient without the need to receive power from the grid. It’s a first rev and isn’t 100% practical, but his research points to practicality through more work on component choice and usage. Whether you need something like this or not, the design process, characterization of components, and testing he did is applicable to all power harvesting projects so check it out!

Did you know there are doorbells that have no batteries in them? Well, kinda. The button you put next to your front door has a piezo element in it (a trick we saw starting about nine years ago). When you press the button it generates just enough juice to squawk out to the receiver — which is itself powered by a wall wart. How often does your doorbell ring? We’d love to see that receiver get some or all of its energy through power harvesting — that is low hanging fruit for an entry. Or, you could repurpose the button unit for other uses. Show us what you’ve got!

Do you remember the battery-less HD video streaming demo that we covered last month? This falls into the category of serious research, but highlights the kind of wacky ideas that might just become reality. This works using backscatter, reflecting the radio waves in the space all around us. It injects an analog HD video signal into that backscatter which is picked up and decoded by a receiving nearby. The camera is meant to be mounted in a pair of glasses and is completely battery-free because it uses RF to power the camera sensors and backscatter system. It’s a great example of doing a lot with the power harvested and stored in a capacitor.

Do It!

This is a fun area of electronics/physics to explore and you’ll learn a lot of interesting stuff just by trying. Our battery technology is slow to make big improvements, so let’s dream up some ways to take more of the effort off of those battery systems. Enter your project in the Power Harvesting Challenge now!

The HackadayPrize2018 is Sponsored by:


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Maison Margiela Spring 2004 

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The reality of Instagram Modeling

This is important.

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