DIY Vacuum Chamber Proves Thermodynamics Professor Isn’t Making It All Up

April 26, 2016 by Gerrit Coetzee 34 Comments

[Mr_GreenCoat] is studying engineering. His thermodynamics teacher agreed with the stance that engineering is best learned through experimentation, and tasked [Mr_GreenCoat]’s group with the construction of a vacuum chamber to prove that the boiling point of a liquid goes down with the pressure it is exposed to.

His group used black PVC pipe to construct their chamber. They used an air compressor to generate the vacuum. The lid is a sheet of lexan with a silicone disk. We’ve covered these sorts of designs before. Since a vacuum chamber is at max going to suffer 14.9 ish psi distributed load on the outside there’s no real worry of their design going too horribly wrong.

The interesting part of the build is the hardware and software built to boil the water and log the temperatures and pressures. Science isn’t done until something is written down after all. They have a power resistor and a temperature probe inside of the chamber. The temperature over time is logged using an Arduino and a bit of processing code.

In the end their experiment matched what they had been learning in class. The current laws of thermodynamics are still in effect — all is right in the universe — and these poor students can probably save some money and get along with an old edition of the textbook. Video after the break.

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Pillaging The Wealth Of Information In A Datasheet

April 26, 2016 by Jenny List 33 Comments

It’s a fair assumption that the majority of Hackaday readers will be used to working with electronic components, they are the life blood of so many of the projects featured here. In a lot of cases those projects will feature very common components, those which have become commoditized through appearing across an enormous breadth of applications. We become familiar with those components through repeated use, and we build on that familiarity when we create our own circuits using them.

All manufacturers of electronic components will publish a datasheet for those components. A document containing all the pertinent information for a designer, including numerical parameters, graphs showing their characteristics, physical and thermal parameters, and some application information where needed. Back in the day they would be published as big thick books containing for example the sheets for all the components of a particular type from a manufacturer, but now they are available very conveniently online in PDF format from manufacturer or wholesaler websites.

Datasheets are a mine of information on the components they describe, but sometimes they can be rather impenetrable. There is a lot of information to be presented, indeed when the device in question is a highly integrated component such as a DSP or microprocessor the datasheet can resemble a medium-sized book. We’re sure that a lot of our readers will be completely at home in the pages of a datasheet, but equally it’s a concern that a section of the Hackaday audience will not be so familiar with them and will not receive their full benefit. Thus we’re going to examine and explain a datasheet in detail, and hopefully shed some light on what it contains.

The device whose datasheet we’ve chosen to put under the microscope is a transistor. The most basic building block of active semiconductor circuits, and the particular one we’ve chosen is a ubiquitous NPN signal transistor, the 2N3904. It’s been around for a very long time, having been introduced by Motorola in the 1960s, and has become the go-to device for a myriad circuits. You can buy 2N3904s made by a variety of manufacturers all of whom publish their own data sheets, but for the purposes of this article we’ll be using the PDF 2N3904 data sheet from ON Semiconductor, the spun-off former Motorola semiconductor division. You might find it worth your while opening this document in another window or printing it out for reference alongside the rest of this article.

Let’s take a look at all the knowledge enshrined in this datasheet, and the engineering eye you sometimes need to assign meaning to those numbers, diagrams, and formulas.

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Retrotechtacular: MONIAC

April 26, 2016 by Jenny List 26 Comments

There is an argument to be made that whichever hue of political buffoons ends up in Number 10 Downing Street, the White House, the Élysée Palace, or wherever the President, Prime Minister or despot lives in your country, eventually they will send the economy down the drain.

Fortunately, there is a machine for that. MONIAC is an analogue computer with water as its medium, designed to simulate a national economy for students. Invented in 1949 by the New Zealand economist [WIlliam Phillips], it is a large wooden board with a series of tanks interconnected by pipes and valves. Different sections of the economy are represented by the water tanks, and the pipes and valves model the flow of money between them. Spending is downhill gravitational water flow, while taxation is represented by a pump which returns money to the treasury at the top. It was designed to represent the British economy in the late 1940s as [Philips] was a student at the London School of Economics when he created it. Using the machine allowed students and economists for the first time to simulate the effects of real economic decisions in government, in real time.

So if you have a MONIAC, you can learn all about spectacularly mismanaging the economy, and then in a real sense flush the economy down the drain afterwards. The video below shows Cambridge University’s restored MONIAC in operation, and should explain the device’s workings in detail.
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DIY Thermal Imaging Smartphone

April 26, 2016 by Elliot Williams 22 Comments

We wish we had [Karri Palovuori] for a professor! As an exciting project to get incoming freshmen stoked on electrical engineering, he designed a DIY thermal-imaging smartphone that they can build themselves. It’s all built to fit into a sleek wooden case that gives the project its name: KAPULA is Finnish for “a block of wood”.

It’s just incredible how far one can push easily-available modules these days. [Karri] mounts a FLIR Lepton thermal camera, an LPC1768 Cortex M3 ARM micro, a GSM phone module, and a whole bunch of other cool stuff on a DIY-friendly two-sided board. The design uses 10 mil (0.25mm) trace and space, which is totally achievable with home etching methods. Copper wire bits fill up the vias. Did we mention he’s making the students do all this themselves? How awesome is that?

[Karri] expects that the students will tweak the software side of things. With additional onboard goodies like an accelerometer, microphone, speaker, SIM card, and USB, it’s not likely that they’ll get bored with the platform. He has a stretch hope that someone will take the hardware and modify it. That’s ambitious for sure, but it’s so cool that someone could.

We’ve seen some sophisticated DIY cellphones before, but this one rises above by being easily DIYable and including awesome extra features. Order parts now, and start etching. You could be sending thermal-photo tweets inside of just a few days.

A Green Powered Sailboat

April 25, 2016 by Brian Benchoff 20 Comments

Drones fill the sky raining hellfire on unsuspecting civilians below. Self-driving cars only cause half as many accidents as carbon-based drivers. Autonomous vehicles are the future, no matter how bleak that future is. One thing we haven’t seen much of is autonomous marine vehicles, be they submarines, hovercrafts, or sailboats. That’s exactly what [silvioBi] is building for his entry into the Hackaday Prize: a sailboat that will ply the waters of Italy’s largest lake.

Every boat needs a hull, but this project will need much more, from electronics to solar panels to sensors. Luckily for [silvio], choosing a hull is as simple as heading over to eBay. [silvio] picked up a fiberglass boat hull for about €40 that fill fit both is needs and his workbench.

The electronics are a bit trickier, but the basic plan is to cover the deck with solar panels, and use a few sensors including GPS, IMU, and an anemometer to steer this sailboat around a lake. Building an autonomous vehicle is a hard challenge, and for the electronics, [silvio] has a trick up his sleeve: he’s using redundant electronics. All the sensors are connected via an I2C bus, so why not put two microcontrollers on that bus in a master and slave configuration? It won’t add much mass, and given the problems had by a few of the teams behind robotic sailing competitions, a bit of redundancy isn’t a bad thing to have.

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USB Soldering Iron Is Surprisingly Capable

April 25, 2016 by Dan Maloney 49 Comments

We know what you’re thinking. There’s no way an 8 watt USB-powered soldering iron could be worth the $5 it commands on eBay. That’s what [BigClive] thought too, so he bought one, put the iron through a test and teardown, and changed his mind. Can he convince you too?

Right up front, [BigClive] finds that the iron is probably not suitable for some jobs. Aside its obvious unsuitability for connections that take a lot of heat, there’s the problem of leakage current when used with a wall-wart USB power supply. The business end of the iron ends up getting enough AC leak through the capacitors of the power supply to potentially damage MOSFETs and the like. Then again, if you’re handy to an AC outlet, wouldn’t you just use a Hakko? Seems like the iron is best powered by a USB battery pack, and [BigClive] was able to solder some surprisingly beefy connections that way. The teardown and analysis reveal a circuit that looks like it came right out of a [Forrest M. Mims III] book. We won’t spoil the surprise for you – just watch the video below.

While not truly cordless like this USB-rechargeable iron, we’d say that for the price, this is a pretty capable iron for certain use cases. Has anyone else tried one of these? Chime in on the comments and let us know what you think.

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Workshops For Timid Solderers

April 25, 2016 by Jenny List 35 Comments

As a hackspace member, it’s easy to fall into the belief that your own everyday skills are universal. Soldering for example. You’ve handled an iron since you were a youngster, the solder bends to your will as a matter of course, and since you see your fellow makers doing the same thing you might imagine that it’s a universal hackspace skill. Everyone can do it, can’t they?

Of course, they can’t. If you weren’t lucky enough to have a parent who tolerated your occasional propensity for acquiring burns on your fingers then you probably won’t have that innate experience with an iron. This extends to people you might expect to have those skills, indeed as an electronic engineering student a couple of decades ago your scribe was surprised to find that the ability to solder was her hotly tradeable skill, amazingly even a lot of EE students couldn’t solder.

So the ability to solder is not as universal as we might expect, and your hackspace will attract plenty of people for whom it is an as-yet-unknown art. What do you do about it? If you are Vancouver Hackspace, you run a workshop whose participants are introduced to soldering through building a simple AM radio. The kit itself is not too special, it looks like one of the Elenco educational kits, but it is what the workshop represents that is important. A hackspace lives or dies by how it shares its skills, and Vancouver’s workshop is a fantastic piece of community engagement. We’d like to see more spaces doing this kind of thing.

So, perhaps it’s time to put our money where our mouth is. How difficult would it be to run a hackspace soldering workshop for the uninitiated? Assuming your space is used to the mechanics of running events, the challenge is to find for each participant a soldering iron, some solder, and a radio or other kit without breaking the bank. An ideal budget from where this is being written in the UK would be £20 (about $29), into which a Chinese kit from AliBaba or similar and a cheap iron kit could be fitted. Some work to decipher the Chinese instructions with the help of an overseas student member and to write an English manual, and we’d be ready to go. If this comes together we’ll report back on whether the non-solderers of our hackspace successfully learned the craft.

We recently featured a similar educational initiative, a course at Swansea Hackspace teaching robotics through an Arduino robot. We would like to encourage this kind of thing, what is your hackspace doing in this line?