The Science Behind Lithium Cell Characteristics And Safety

September 18, 2017 by Sean Boyce 58 Comments

To describe the constraints on developing consumer battery technology as ‘challenging’ is an enormous understatement. The ideal rechargeable battery has conflicting properties – it has to store large amounts of energy, safely release or absorb large amounts of it on demand, and must be unable to release that energy upon failure. It also has to be cheap, nontoxic, lightweight, and scalable.

As a result, consumer battery technologies represent a compromise between competing goals. Modern rechargeable lithium batteries are no exception, although overall they are a marvel of engineering. Mobile technology would not be anywhere near as good as it is today without them. We’re not saying you cannot have cellphones based on lead-acid batteries (in fact the Motorola 2600 ‘Bag Phone’ was one), but you had better have large pockets. Also a stout belt or… some type of harness? It turns out lead is heavy.

The Motorola 2600 ‘bag phone’, with a lead-acid battery. Image CC-BY-SA 3.0 source: Trent021

Rechargeable lithium cells have evolved tremendously over the years since their commercial release in 1991. Early on in their development, small grains plated with lithium metal were used, which had several disadvantages including loss of cell capacity over time, internal short circuits, and fairly high levels of heat generation. To solve these problems, there were two main approaches: the use of polymer electrolytes, and the use of graphite electrodes to contain the lithium ions rather than use lithium metal. From these two approaches, lithium-ion (Li-ion) and lithium-polymer (Li-Po) cells were developed (Vincent, 2009, p. 163). Since then, many different chemistries have been developed.

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In-Band Signaling: Coded Squelch Systems

September 13, 2017 by Dan Maloney 18 Comments

In the first part of our series on in-band signaling, we discussed one of the most common and easily recognizable forms of audio control, familiar to anyone who has dialed a phone in the last fifty years – dual-tone multifrequency (DTMF) dialing. Our second installment will look at an in-band signaling method that far fewer people have heard, precisely because it was designed to be sub-audible — coded squelch systems for public service and other radio services. Continue reading “In-Band Signaling: Coded Squelch Systems” →

The Components Are INSIDE The Circuit Board

September 11, 2017 by Bob Baddeley 56 Comments

Through-hole assembly means bending leads on components and putting the leads through holes in the circuit board, then soldering them in place, and trimming the wires. That took up too much space and assembly time and labor, so the next step was surface mount, in which components are placed on top of the circuit board and then solder paste melts and solders the parts together. This made assembly much faster and cheaper and smaller.

Now we have embedded components, where in order to save even more, the components are embedded inside the circuit board itself. While this is not yet a technology that is available (or probably even desirable) for the Hackaday community, reading about it made my “holy cow!” hairs tingle, so here’s more on a new technology that has recently reached an availability level that more and more companies are finding acceptable, and a bit on some usable design techniques for saving space and components.

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Knowing What’s Below: Buried Utility Location

September 7, 2017 by Dan Maloney 54 Comments

We humans have put an awful lot of effort into our infrastructure for the last few centuries, and even more effort into burying most of it. And with good reason — not only are above ground cables and pipes unsightly, they’re also vulnerable to damage from exposure to the elements. Some utilities, like natural gas and sanitary sewer lines, are also dangerous, or at least perceived to be so, and so end up buried. Out of sight, out of mind.

But humans love to dig, too, and it seems like no sooner is a paving project completed than some joker with a jackhammer is out there wrecking the pristine roadway. Before the construction starts, though, cryptic markings will appear on the pavement courtesy of your local buried utility locating service, who apply their rainbow markings to the ground so that nothing bad happens to the often fragile infrastructure below our feet.

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In-Band Signaling: Dual-Tone Multifrequency Dialing

September 5, 2017 by Dan Maloney 43 Comments

One late night many decades ago, I chanced upon a technical description of the Touch-Tone system. The book I was reading had an explanation of how each key on a telephone sends a combination of two tones down the wire, and what’s more, it listed the seven audio frequencies needed for the standard 12-key dial pad. I gazed over at my Commodore 64, and inspiration hit — if I can use two of the C64’s three audio channels to generate the dual tones, I bet I can dial the phone! I sprang out of bed and started pecking out a Basic program, and in the wee hours I finally had it generating the recognizable Touch-Tones of my girlfriend’s phone number. I held the mouthpiece of my phone handset up to the speaker of my monitor, started the program, and put the receiver to my ear to hear her phone ringing! Her parents were none too impressed with my accomplishment since it came at 4:00 AM, but I was pretty jazzed about it.

Since that fateful night I’ve always wondered about how the Touch-Tone system worked, and in delving into the topic I discovered that it’s part of a much broader field of control technology called in-band signaling, or the use of audible or sub-audible signals to control an audio or video transmission. It’s pretty interesting stuff, even when it’s not used to inadvertently prank call someone in the middle of the night. Continue reading “In-Band Signaling: Dual-Tone Multifrequency Dialing” →

How Peptides Are Made

August 22, 2017 by Will Sweatman 28 Comments

What does body building, anti-aging cream and Bleomycin (a cancer drug) have in common? Peptides of course! Peptides are large molecules that are vital to life. If you were to take a protein and break it into smaller pieces, each piece would be called a peptide. Just like proteins, peptides are made of amino acids linked together in a chain-like structure. Whenever you ingest a protein, your body breaks it down to its individual amino acids. It then puts those amino acids back together in a different order to make whatever peptide or protein your body needs. Insulin, for instance, is a peptide that is 51 amino acids long. Your body synthesizes insulin from the amino acids it gets from the proteins you eat.

Peptides and small proteins can be synthesized in a lab as well. Peptide synthesis is a huge market in the pharmaceutical and skin care industry. They’re also used, somewhat shadily, as a steroid substitute by serious athletes and body builders. In this article, we’re going to go over the basic steps of how to join amino acids together to make a peptide. The chemistry of peptide synthesis is complex and well beyond the scope of this article. But the basic steps of making a peptide are not as difficult as you might think. Join me after the break to gain a basic understanding of how peptides are synthesized in labs across the world, and to establish a good footing should you ever wish to delve deeper and make peptides on your own.

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The Enigma Enigma: How The Enigma Machine Worked

August 22, 2017 by Steven Dufresne 32 Comments

To many, the Enigma machine is an enigma. But it’s really quite simple. The following is a step-by-step explanation of how it works, from the basics to the full machine.

Possibly the greatest dedicated cipher machine in human history the Enigma machine is a typewriter-sized machine, with keyboard included, that the Germans used to encrypt and decrypt messages during World War II. It’s also one of the machines that the Polish Cipher Bureau and those at Britain’s Bletchley Park figured out how to decipher, or break. Most recently the story of how it was broken was the topic of the movie The Imitation Game.

Let’s start with the basics.

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