Ask Hackaday: What Should Father Christmas Bring From Shenzhen?

Imagine this, you have a friend who grew up in Shenzhen, China. The place from whence all your really cool electronics come these days. They speak Chinese in a way only someone born there can, and given that you know them through a shared interest in hardware hacking you can assume they know their way round those famous electronics marts of their home town.

Now, imagine that in a rash move, your friend has offered to pick up a few bits for you on their next trip home. A whole city-sized electronic candy store opens up in front of you, but what do you ask for them to seek out?

Before you continue, consider this. Why has Shenzhen become the powerhouse of electronic manufacturing (and everything else) that it is? Economists will give you pages of fascinating background, but if you want a simple answer it is that those electronics are produced for export, and that its citizens are only too happy to export them to you. Therefore if you want to get your hands on electronics from Shenzhen you do not need a friend who is a native of the city, all you need is a web browser and a PayPal account.

We have all become used to seeking out the cool stuff and eagerly waiting for a padded envelope from China Post a week or two later, so there are very few items that are worth putting a friend to the extra task of finding. At which point you realize that it is the candy store rather than the candy itself which is so alluring, and you ask your friend for a video walkthrough with commentary of their travels through the electronics marts. Oh, and maybe a Chinese Raspberry Pi with red solder resist, just for the collection.

If you had a friend about to board a plane to Shenzhen, what would you ask them to find for you that you can’t just buy for yourself online? Remember, nothing that’ll land them with awkward questions at either airport, nor anything that’ll land them with a hefty customs bill. That’s a very good way to end a friendship.

Huaqiangbei skyline image: Edward Rivens (PD) via Wikimedia Commons.

Electronica 2016: Too Much Electronics

The Electronica trade show in Munich is so big that it only takes place once every two years. Every manufacturer, distributor, and maker of anything electronic is there. To get a feel for the scale of things, Electronica is spread out over twelve large exhibition halls and is served by two separate subway stations, one on either end. You wouldn’t think there would be so many inductor manufacturers in the world, but you’d be wrong.

dscf9020It’s a hardware geek’s paradise, even if it is aimed more at facilitating industry contacts than at serving the humble hacker. But it’s great to see what is out there, quiz reps of all our favorite chip manufacturers about what they’ve got going on, and just generally wander around. You might not get to play with the multi-gigahertz scopes on a day-to-day basis, but you can get hands-on with them at Electronica. And as cool as it is to talk directly to the representatives of our mega-manufacturers, it’s maybe more fun to check up on the creative fringe of companies that you’ve never heard of before, but who nonetheless have great ideas.
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A Short Introduction to Staking and Potting

Staking and potting are not often used in the hobby electronics world, not really entering to the common vernacular. However, everyone who’s ever busted out a glue-gun to convince that dang wire that keeps coming loose to stay has done it.

However, as [Sean Thomas] touches on, staking is not necessarily as easy as a dob of hot glue. There is a method to the madness. [Sean] gives some examples in pictures, but also directs people to the excellent NASA standard methods for staking. It’s surprising how many unintuitive caveats there are to the proper technique.

Potting, or covering everything in epoxy forever, is a great way to get a waterproof, unserviceable, and practically mechanically invincible circuit. The big challenge in potting is picking the right material. A soft silicone, for example, might transfer an unexpected force to an unexpected section of the circuit and cause a mechanical failure. A nice hard epoxy may be too insulating and cause a thermal failure. The standard RTV from the big box store has acetic acid that will eat your components.

These two techniques that come in handy when you need them and worth the bit of reading it takes to get familiar. Have you used either in your own workshop? Let us know the application and the material/techniques you have tried in the comments below.

Portable Workbench Crams An Entire Workspace Into One Box

Making on the go is sometimes required in today’s busy lives, and if you find yourself traveling — say, off to university like [ZSNRA] — then a convenient solution is required. To that end, a portable electronics workbench was built in the shape of a relatively nondescript plywood box.

Plywood and foam-core are the main materials used in building this maker’s bug-out box, with two fir runners along the bottom so the case is not resting on the hinges. Inside, [ZSNRA] has packed a staggering amount of hardware which results in an 11kg suitcase.

Power StackHere goes — deep breath now: wires, solder, resistors, transistors, capacitors, diodes, clips, switches, logic chips, non-logic chips, an Arduino, ATmegas, fuses, pliers, wire strippers and cutters, angle cutters, tweezers, a 66-piece screwdriver set, a desoldering pump, 12 needle files, a hacksaw blade, a multi meter, oscilloscope, power source, four outlets built into the case(!), steel wool, a third hand, a soldering station, two handbooks, and a breadboard.

Whew.

 

The work surface is an ESD mat on the inside of the case’s front face that is comfortable enough to work with, though we are surprised that it doesn’t also fold out somehow to create an even larger work-space.

For an elegant — if slightly less mobile — workbench solution, check out The Tempel. Now if you’re looking for ideas on how and what to carry we still think [Kenji Larsen] has the ultimate hacking kit.

[Thanks for the tip, Zaphod! via /r/electronics]

Books You Should Read: Basic Electronics

I learned some basic electronics in high school physics class: resistors, capacitors, Kirchoff’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 12th Edition
Grob’s Basic Electronics 12th Edition

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.

You can find the table of contents here but briefly it has all the necessary introductory material on Ohm’s and Kirchoff’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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Super In-Depth $15 Curve Tracer Project

[Jason Jones] has always wanted a curve tracer for his home shop. When he was starting out in electronics he fell in love with a machine called a Huntron Tracker 2000. This machine would feed a sine wave into a circuit on one side and plot a XY graph on the other.

[Jason] figured that with a modern microcontroller such a device could be build simply and cheaply for around $15 dollars. With that requirement in mind he set out to build it. He selected a PIC24F16KM202 for the brain and got to work.

The write-up is really great. It’s rare that someone puts every step of their development and design thinking into writing. Some have argued that this is the only true way to have an OSHW hardware project. The series covers everything from the initial requirements and parts selection to the software development and eventual testing of the device.

[Jason] managed to build a pretty capable little curve tracer in the end. We really enjoyed it when he used the tracer to debug the tracer.

JIT Learning Using Expert Systems

Chris Gammell is a guy that should need no introduction around these parts. He’s a co-host on The Amp Hour, and the guy behind Contextual Electronics, a fabulous introduction to electronics and one of the best ways to learn KiCad. If you want to talk about the pedagogy of electronics, this is the guy you want.

Chris’ talk at the Hackaday | Belgrade conference was on just that – the pedagogy of electronics. Generally, there are two ways to learn how to blink an LED. The first, the bottom-up model taught in every university, is to first learn Ohm’s law, resistance, current, voltage, solve hundreds of resistor network problems, and eventually get around to the ‘electrons and holes’ description of a semiconductor. The simplest semiconductor is a diode, and sometime in the sophomore or junior year, the student will successfully blink a LED.

The second, top-down method is much simpler. Just wire up a battery, resistor, switch, and LED to a breadboard. This is the top-down model of electronics design; you don’t need to know everything to get it to work. You don’t need to do it with a 555, and you certainly don’t have to derive Maxwell’s equations to make something glow. Chris is a big proponent of the top-down model of learning, and his Belgrade talk is all about the virtues of not knowing everything.

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