Guide: Why Etch a PCB When You Can Mill?

I recall the point I started taking electronics seriously, although excited, a sense of dread followed upon the thought of facing the two main obstacles faced by hobbyists and even professionals: Fabricating you own PCB’s and fiddling with the ever decreasing surface mount footprints. Any resistance to the latter proves futile, expensive, and frankly a bit silly in retrospect. Cheap SMD tools have made it extremely easy to store, place, and solder all things SMD.

Once you’ve restricted all your hobbyist designs/experiments to SMD, how do you go about producing the PCBs needed for prototyping? Personally, I dread the thought of etching my own boards. The process is laborious and involves messy chemicals and specially sensitized PCB’s — none of which interest me. I’ve only ever done it a few times, and have promised myself never to do it again. Professional but cheap PCB manufacturing is more like it board pooling services such as OSH park have made this both easy and affordable — if you can wait for the turnaround.

So what are the alternatives? If you are really serious about swift prototyping from your own Lab, I put forth the case of milling your own PCB’s. Read on as I take you through the typical workflow from design to prototype and convince you to put up with the relatively high start up cost of purchasing a PCB mill.

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Learning ARM assembly with visUAL

Learning assembly is very important if you want to get a grasp of how a computer truly works under the hood. VisUAL is a very capable ARM emulator for those interested in learning the ARM assembly.

The GUI: A simply program to ADD two numbers

In addition to supporting a large subset of ARM instructions, the CPU is emulated via a series of elaborate and instructive animations that help visualise the flow of data to/from registers, any changes made to flags, and any branches taken. It also packs very useful animations to help grasp some of the more tricky instruction such as shifts and stack manipulations.

As it is was designed specifically to be used as teaching tool at Imperial College London, the GUI is very friendly, all the syntax errors are highlighted, and an example of the correct syntax is also shown.

Branch visualisation, credits: VisUAL homepage

You can also do the usual things you would expect from any emulator, such as single step through execution, set breakpoints, and view data in different bases. It even warns you of any possible infinite loops!

That being said, lugging such an extravagant GUI comes at a price; programs that consume a few hundred thousand cycles hog far too much RAM should be run in the supported headless mode.


Programmable Christmas Tree is a JavaScript Interpreter

Here at Hackaday, we find Christmas time very exciting because it means an influx of holiday-themed hacks that really help us get into the festive mood. [Andrew’s] programmable Christmas tree hosted at HackMyXmas is certainly one of our favorites. The project consists of a 500 RGB LEDs wrapped around a typical Christmas tree and controlled by a Teensy.  However, not settling for the typical, simple and cyclical pattern for the LEDs, [Andrew] decided the tree had to be programmable of course! So, a single board computer (a C.H.I.P) running Linux was used to provide a Wifi connection and a web server to easily program the tree.

This is where things get very interesting. The C.H.I.P board hosts a comprehensive website that conveniently gives you the option to program the LEDs using either, Scratch like draggable blocks (using Googles Blockly) or even pure JavaScript. Once the perfect pattern is conceived, you can test run it on the online simulator or even send it off straight to the Tree, watching it blink in all its glory on the provided live stream.

We applaud [Andrew] mammoth effort for invoking programming in such a fun way! You can check out the live stream of [Andrew]’s Christmas tree below.

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Control a Quadcopter over Websockets

The interface

Everyone’s favourite IOT module, the ESP8266, is often the go-to choice for any project that needs quick and cheap control over the web. [Andi23456] wanted to control his quadcopter using the luxury of his mobile phone and thought permanently tethering an ESP12-E module to the quadcopter was exactly what he required.

The ESP8266, really showcasing its all-round prowess, hosts both a web server for a HTML5 based joystick and a Websockets server so that a client, such as a phone, could interact with it over a fast, low latency connection. Once the ESP8266 receives the input, it uses interrupts to generate the corresponding PPM (Pule Position Modulation) code which the RC receiver on the quadcopter can understand. Very cool!

What really makes this realtime(ish) control viable is Websockets, a protocol that basically allows you to flexibly exchange data over an “upgraded” HTTP connection without having to lug around headers each time you communicate. If you haven’t heard of Websockets you really should look really check out this library or even watch this video to see what you can achieve.

Salvaging Your Way to a Working Tesla Model S for $6500

If you possess modest technical abilities and the patience of a few dozen monks, with some skillful haggling you can land yourself some terrific bargains by salvaging and repairing. This is already a well-known ideology when it comes to sourcing things like electronic test gear, where for example a non working unit might be purchased from eBay and fixed for the price of a few passive components.

[Rich] from Car Guru has taken this to a whole new level by successfully salvaging a roadworthy Tesla Model S for $6500!

Sourcing and rebuilding a car is always a daunting project, in this case made even more challenging because the vehicle in subject is fairly recent, state of the art electric vehicle. The journey began by purchasing a black Tesla Model S, that [Rich] affectionately refers to as Delorean. This car had severe water damage rendering most of its electronics and mechanical fasteners unreliable, so [Rich’s] plan was to strip this car of all such parts, and sell what he could to recover the cost of his initial purchase. After selling the working modules of the otherwise drenched battery, motor and a few other bells and whistles his initial monetary investment was reduced to the mere investment of time.

With an essentially free but empty Tesla shell in his possession, [Rich] turned his attention to finding a suitable replacement for the insides. [Rich] mentions that Tesla refused to sell spare parts for such a project, so his only option was to purchase a few more wrecked vehicles. The most prominent of these wrecks was nicknamed Slim Shady. This one

The Donor

had an irreparable shell but with most electronics preserved, and would serve as the donation vehicle. After painstakingly transplanting all the required electronics and once again selling what he did not need, his net investment came to less than 10% of a new car!

Was all of the effort worth it? We certainly think it was! The car was deemed road worthy and even has functioning Super Charging capabilities which according to [Rich] are disabled by Tesla if such a Frankenstein build is detected.

At this point it would probably be instructive to ask [Rich] if he would do it again, but he is already at it, this time salvaging the faster self driving P86. We suggest you stay tuned.

[Thankyou to Enio Fernandes for sending in the tip]

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3D Prints That Fold Themselves

3D printing technologies have come a long way, not only in terms of machine construction and affordability but also in the availability of the diverse range of different printing materials at our disposal. The common consumer might already be familiar with the usual PLA, ABS but there are other more exotic offerings such as PVA based dissolvable filaments and even carbon fiber and wood infused materials. Researchers at MIT allude to yet another possibility in a paper titled “3D-Printed Self-Folding Electronics” also dubbed the “Peel and Go” material.

The crux of the publication is the ability to print structures that are ultimately intended to be intricately folded, in a more convenient planar arrangement. As the material is taken off the build platform it immediately starts to morph into the intended shape. The key to this behavior is the use of a special polymer as a filler for joint-like structures, made out of more traditional but flexible filament. This special polymer, rather atypically, expands after printing serving almost like a muscle to contort the printed joint.

Existing filaments that can achieve similar results, albeit after some manual post-processing such as immersion in water or exposure to heat are not ideal for electronic circuits. The researchers focus on this new materials potential use in manufacturing electronic circuits and sensors for the ever miniaturizing consumer electronics.

If you want to experiment printing extremely intricate structures, check out how [_primoz_] brilliant technique revolutionized how the 3D printing community prints thin fibers, bristles, and lion sculptures.

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A 3D Printed Junction Transistor Model

Transistors are no doubt one of humankinds greatest inventions. However, the associated greatness brings with it unprecedented complexity under the hood. To fully understand how a transistor works, one needs to be familiar with some Quantum Mechanics! As perhaps any EE undergraduate would tell you, one of the hardest subject to fathom is in fact semiconductor physics.

Take your pick: Mathematical equations governing the various currents inside a BJT

A good place to start to comprehend anything complex is by having an accurate but most importantly, tangible model at hand. Semiconductors are hard enough to describe with elaborate mathematical tools, is a physical model too much to ask?

[Chuck] has designed, printed and explained the workings of a BJT transistor using a 3D printed model. We really like this model because it goes a long way to shed light on some of the more subtle features of BJT transistors for beginners.

For example, the simplest “electronic switch” model completely ignores the application of a transistor as a linear amplifier and cannot be used to explain important transistor parameters such as hfe (DC current gain Beta) or the VBE (voltage to forward bias the base-emitter junction). [Chuck’s] model on the other hand certainly offers better intuition on these, as the former can be linked to the length of the levers arm and the latter to the minimum force needed to rotate the lever. The Tee structure even signifies the combination of base current with the collector current during operation!

If physical models are not your thing, the classic pictorial depiction, the “Transistor Man” in the Art of Electronics might be of interest. If you’ve even outgrown that, its time to dig into the quantum mechanics involved.

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