Books You Should Read: Basic Electronics

August 19, 2016 by Steven Dufresne 40 Comments

I learned some basic electronics in high school physics class: resistors, capacitors, Kirchhoff’s law and such, and added only what was required for projects as I did them. Then around 15 years ago I decided to read some books to flesh out what I knew and add to my body of knowledge. It turned out to be hard to find good ones.

The electronics section of my bookcase has a number of what I’d consider duds, but also some gems. Here are the gems. They may not be the electronics-Rosetta-Stone for every hacker, but they are the rock on which I built my church and well worth a spot in your own reading list.

Grob’s Basic Electronics

Grob’s Basic Electronics by Mitchel E Schultz and Bernard Grob is a textbook, one that is easy to read yet very thorough. I bought mine from a used books store. The 1st Edition was published in 1959 and it’s currently on the 12th edition, published in 2015. Clearly this one has staying power.

I refer back to it frequently, most often to the chapters on resonance, induction and capacitance when working on LC circuits, like the ones in my crystal radios. There are also things in here that I couldn’t find anywhere else, including thoroughly exhaustive online searches. One such example is the correct definitions and formulas for the various magnetic units: ampere turns, field intensity, flux density…

I’d recommend it to a high school student or any adult who’s serious about knowing electronics well. I’d also recommend it to anyone who wants to reduce frustration when designing or debugging circuits.

Series-Resonance calculations

Series-Resonance schematic

You can find the table of contents here but briefly it has all the necessary introductory material on Ohm’s and Kirchhoff’s laws, parallel and series circuits, and so on but to give you an idea of how deep it goes it also has chapters on network theorems and complex numbers for AC circuits. Interestingly my 1977 4th edition has a chapter on vacuum tubes that’s gone in the current version and in its place is a plethora of new ones devoted to diodes, BJTs, FETs, thyristors and op-amps.

You can also do the practice problems and self-examination, just to make sure you understood it correctly. (I sometimes do them!) But also, being a textbook, the newest edition is expensive. However, a search for older but still recent editions on Amazon turns up some affordable used copies. Most of basic electronics hasn’t changed and my ancient edition is one of my more frequent go-to books. But it’s not the only gem I’ve found. Below are a few more.

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Asking The Security Question Of Home Automation

August 18, 2016 by Mike Szczys 53 Comments

“Security” is the proverbial dead horse we all like to beat when it comes to technology. This is of course not unjust — we live in a technological society built with a mindset of “security last”. There’s always one reason or another proffered for this: companies need to fail fast and will handle security once a product proves viable, end users will have a harder time with setup and use if systems are secured or encrypted, and governments/law enforcement don’t want criminals hiding behind strongly secured systems.

This is an argument I don’t want to get bogged down in. For this discussion let’s all agree on this starting point for the conversation: any system that manages something of value needs some type of security and the question becomes how much security makes sense? As the title suggests, the technology du jour is home automation. When you do manage to connect your thermostat to your door locks, lights, window shades, refrigerator, and toilet, what type of security needs to be part of the plan?

Join me after the break for an overview of a few Home Automation security concerns. This article is the third in our series — the first asked What is Home Automation and the second discussed the Software Hangups we face.

These have all been inspired by the Automation challenge round of the Hackaday Prize. Document your own Automation project by Monday morning to enter. Twenty projects will win $1000 each, becoming finalists with a chance at the grand prize of $150,000. We’re also giving away Hackaday T-shirts to people who leave comments that help carry this discussion forward, so let us know what you think below.

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Hackaday NYC Summer Party

August 17, 2016 by Brian Benchoff 7 Comments

Hackaday is going to be back in NYC next week, and we’re having a meetup. This isn’t any meetup – it’s a meetup with skeeball. No, it does not get any better than this.

Next week, August 24, at 6:30pm, we’re pulling out all the stops at Ace Bar on the Lower East Side. This event is a bring-a-hack, and we want to see what you’re working on. Bring your current project, an oscilloscope demo, blinkey clothing, hacks, wearables, or just some cool, random junk. The last time we did this, someone brought a flight data recorder from a Pan Am 747. It had 74-series and 54-series logic chips in it, and no one could figure out why.

This event will be hosted by our lovely multi-function unicorn @SophiKravitz and our NYC community manager @Shayna. Bring your friends, and bring your projects, this isn’t an event to miss.

Fail Of The Week: How NOT To Smooth A 3D Print

August 16, 2016 by Dan Maloney 78 Comments

Many of the Fail Of The Week stories we feature here are pretty minor in the grand scheme of things. At worse, gears are ground, bits are broken, or the Magic Blue Smoke is released. This attempt to smooth a 3D print released far more than a puff of blue smoke, and was nearly a disaster of insurance adjuster or medical examiner proportions.

Luckily, [Maxloader] and his wife escaped serious injury, and their house came out mostly unscathed. The misadventure started with a 3D printed Mario statue. [Maxloader] had read acetone vapor can smooth a 3D print, and that warming the acetone speeds the process. Fortunately, his wife saw the looming danger and wisely suggested keeping a fire blanket handy, because [Max] decided to speed the process even more by putting a lid on the pot. It’s not clear exactly what happened in the pot – did the trapped acetone vapors burp the lid off and find a path to the cooktop burner? Whatever it was, the results were pretty spectacular and were captured on a security camera. The action starts at 1:13 in the video below. The fire blanket came in handy, buying [Max] a few seconds to open the window and send the whole flaming mess outside. Crisis averted, except for nearly setting the yard on fire.

What are we to learn from [Maxloader]’s nearly epic fail? First, acetone and open flame do not mix. If you want to heat acetone, do it outside and use an electric heat source. Second, a fire extinguisher is standard household equipment. Every house needs at least one, and doubly so when there’s a 3D printer present. And third, it’s best to know your filaments – the dearly departed Mario print was in PLA, which is best smoothed with tetrahydrofuran, not acetone.

Anything else? Feel free to flame away in the comments.

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Retrotechtacular: Tom Carter Revolutionized Your Phone

August 16, 2016 by Al Williams 40 Comments

It is hard to remember, but there was a time when you couldn’t hook much to a telephone line except a telephone. Although landlines are slowly falling out of favor, you can still get corded and wireless phones, answering machines, and even dial up modems. Alarm systems sometimes connect to the phone system along with medical monitoring devices and a host of other accessories.

All of that’s possible because of a Texan named Tom Carter. Tom Carter was the David that stood up to one of the biggest Goliath’s of his day: the phone company. The phone company had a legal monopoly on providing phone service. The reasoning was that it didn’t make sense to have multiple competing companies trying to run wires to every house and business in the country. Makes sense, right?

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Ask Hackaday: What Are Magnetic Gears (Good For)?

August 15, 2016 by Moritz Walter 51 Comments

Magnetic gears are surprisingly unknown and used only in a few niche applications. Yet, their popularity is on the rise, and they are one of the slickest solutions for transmitting mechanical energy, converting rotational torque and RPM. Sooner or later, you’re bound to stumble upon them somewhere, so let’s check them out to see what they are and what they are good for.

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History Of The Diode

August 15, 2016 by Steven Dufresne 46 Comments

The history of the diode is a fun one as it’s rife with accidental discoveries, sometimes having to wait decades for a use for what was found. Two examples of that are our first two topics: thermionic emission and semiconductor diodes. So let’s dive in.

Vacuum Tubes/Thermionic Diodes

Our first accidental discovery was of thermionic emission, which many years later lead to the vacuum tube. Thermionic emission is basically heating a metal, or a coated metal, causing the emission of electrons from its surface.

In 1873 Frederick Guthrie had charged his electroscope positively and then brought a piece of white-hot metal near the electroscope’s terminal. The white-hot metal emitted electrons to the terminal, which of course neutralized the electroscope’s positive charge, causing the leafs to come together. A negatively charged electroscope can’t be discharged this way though, since the hot metal emits electrons only, i.e. negative charge. Thus the direction of electron flow was one-way and the earliest diode was born.

Thomas Edison independently discovered this effect in 1880 when trying to work out why the carbon-filaments in his light bulbs were often burning out at their positive-connected ends. In exploring the problem, he created a special evacuated bulb wherein he had a piece of metal connected to the positive end of the circuit and held near the filament. He found that an invisible current flowed from the filament to the metal. For this reason, thermionic emission is sometimes referred to as the Edison effect.

Thermionic diode. By Svjo [CC BY-SA 3.0], via Wikimedia Commons

But it took until 1904 for the first practical use of the effect to appear. John Ambrose Fleming had actually consulted for the Edison Electric Light Company from 1881-1891 but was now working for the Marconi Wireless Telegraph Company. In 1901 the company demonstrated the first radio transmission across the Atlantic, the letter “S” in the form or three dots in Morse code. But there was so much difficulty in telling the received signal apart from the background noise, that the result was disputed (and still is). This made Fleming realize that a more sensitive detector than the coherer they’d been using was needed. And so in 1904 he tried an Edison effect bulb. It worked well, rectifying the high frequency oscillations and passing the signals on to a galvanometer. He filed for a patent and the Fleming valve, the two element vacuum tube or thermionic diode, came into being, heralding decades of technological developments in many subsequent types of vacuum tubes.

Vacuum tubes began to be replaced in power supplies in the 1940s by selenium diodes and in the 1960s by semiconductor diodes but are still used today in high power applications. There’s also been a resurgence in their use by audiophiles and recording studios. But that’s only the start of our history.

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