Chaos Communication Camp 2015 is over, and most everyone’s returned home to warmer showers and slower Internet. In this last transmission from Camp 2015, we’ll cover the final two days of talks, the epic thunderstorm, and give a brief rundown of the challenges of networking up a rural park in Brandenburg.
Chances are pretty good you’ve had a glowing probe clipped to your fingertip or earlobe in some clinic or doctor’s office. If you have, then you’re familiar with pulse oximetry, a cheap and non-invasive test that’s intended to measure how much oxygen your blood is carrying, with the bonus of an accurate count of your pulse rate. You can run down to the local drug store or big box and get a fingertip pulse oximeter for about $25USD, but if you want to learn more about photoplethysmography (PPG), [Rajendra Bhatt]’s open-source pulse oximeter might be a better choice.
PPG is based on the fact that oxygenated and deoxygenated hemoglobin have different optical characteristics. A simple probe with an LED floods your fingertip with IR light, and a photodiode reads the amount of light reflected by the hemoglobin. [Rajendra]’s Easy Pulse Plugin receives and amplifies the signal from the probe and sends it to a header, suitable for Arduino consumption. What you do with the signal from there is up to you – light an LED in time with your heartbeat, plot oxygen saturation as a function of time, or drive a display to show the current pulse and saturation.
We’ve seen some pretty slick DIY pulse oximeters before, and some with a decidedly home-brew feel, but this seems like a good balance between sophisticated design and open source hackability. And don’t forget that IR LEDs can be used for other non-invasive diagnostics too.
The 2015 Hackaday Prize is sponsored by:
It’s sometimes hard to believe how stuff was made over a hundred years ago when electricity wasn’t widely available. One of the most common ways of powering tools was via belt drive — powered by a water mill, or a steam engine, or even horses. [David Richards] has spent a good chunk of time making his own period accurate steam powered machine shop — and it’s fantastic.
It represents approximately what a 1920’s machine shop would look like in America. Not a single tool is newer than 1925. The whole shop is powered by a line shaft using steam power. A massive boiler provides steam for a Pennsylvania built 5 by 5 steam engine, dating back to approximately 1895. Using belts and clutches, it powers a few lathes, drill presses, a mill, and even a shaper — an identical machine to one in the Edison Museum!
It takes strong and determined population to build a lasting civilization. If the civilization includes electricity and the inhabitants live in a hilly place with an often-unforgiving climate, the required strength and determination increases proportionally. Such is the case of the gentlemen who strung up the first half-million VDC transmission line across New Zealand, connecting the country’s two main islands.
Construction for the line known as the HVDC Inter-Island link began in 1961. It starts at the Benmore hydroelectric plant on the south island and runs north to Cook Strait via overhead cables. Then it travels 40km underwater to the north island and ends near Wellington. This is the kind of infrastructure project that required smaller, preliminary infrastructure projects. Hundreds of miles of New Zealand countryside had to be surveyed before breaking ground for the first tower support hole. In order to transport the materials and maintain the towers, some 270 miles of road were laid and ten bridges were built. Fifteen camps were set up to house the workers.
The country’s hilly terrain and high winds made the project even more challenging. But as you’ll see, these men were practically unfazed. They sent bundles of steel across steep canyons on zip lines and hand-walked wire haulage rope across gullies because they couldn’t otherwise do their job. Six of these men could erect a tower within a few hours, which the filmmakers prove with a cool time-lapse sequence.
Splicing the mile-long conductors is done with 100-ton compressors. Each connection is covered with steel sleeve that must be centered across the joint for optimum transmission. How did they check this? By taking a bunch of x-rays with a portable cesium-137 source.
Over the last year we’ve had several posts about the Lattice Semiconductor iCEstick which is shown below. The board looks like an overgrown USB stick with no case, but it is really an FPGA development board. The specs are modest and there is a limited amount of I/O, but the price (about $22, depending on where you shop) is right. I’ve wanted to do a Verilog walk through video series for awhile, and decided this would be the right target platform. You can experiment with a real FPGA without breaking the bank.
In reality, you can learn a lot about FPGAs without ever using real hardware. As you’ll see, a lot of FPGA development occurs with simulated FPGAs that run on your PC. But if you are like me, blinking a virtual LED just isn’t as exciting as making a real one glow. However, for the first two examples I cover you don’t need any hardware beyond your computer. If you want to get ready, you can order an iCEstick and maybe it’ll arrive before Part III of this series if published.
Yesterday Google announced preorders for a new device called OnHub. Their marketing, and most of the coverage I’ve seen so far, touts OnHub as a better WiFi router than you are used to including improved signal, ease of setup, and a better system to get your friends onto your AP (using the ultrasonic communication technique we’ve also seen on the Amazon Dash buttons). Why would Google care about this? I don’t think they do, at least not enough to develop and manufacture a $199.99 cylindrical monolith. Nope, this is all about the Internet of Things, as much as it pains me to use the term.
OnHub boasts an array of “smart antennas” connected to its various radios. It has the 2.4 and 5 Gigahertz WiFi bands in all the flavors you would expect. The specs also show an AUX Wireless for 802.11 whose purpose is not entirely clear to me but may be the network congestion sensing built into the system (leave a comment if you think otherwise). Rounding out the communications array is support for ZigBee and Bluetooth 4.0.
I have long looked at Google’s acquisition of Nest and assumed that at some point Nest would become the Router for your Internet of Things, collecting data from your exercise equipment and bathroom scale which would then be sold to your health insurance provider so they may adjust your rates. I know, that’s a juicy piece of Orwellian hyperbole but it gets the point across rather quickly. The OnHub is a much more eloquent attempt at the same thing. Some people were turned off by the Nest because it “watches” you to learn your heating preferences. The same issue has arisen with the Amazon Echo which is “always listening”.
Google has foregone those built-in futuristic features and chosen a device to which almost everyone has already grown accustom: the WiFi router. They promise better WiFi and I’m sure it will deliver. What’s the average age of a home WiFi AP at this point anyway? Any new hardware would be an improvement. Oh, and when you start buying those smart bulbs, fridges, bathroom scales, egg trays, and whatever else it’ll work for them as well.
As far as hacking and home automation, it’s hard to beat the voice-activated commands we’ve seen with Echo lately, like forcing it to control Nest or operate your Roku. Who wants to bet that we’ll see a Google-Now based IoT standalone device quickly following the shipment of OnHub?
There is a device under test out there that promises to take humans to another star in a single lifetime. It means vacations on the moon, retiring at Saturn, and hovercars. If it turns out to be real, it’s the greatest invention of the 21st century. If not, it will be relegated to the history of terrible science right underneath the cold fusion fiasco. It is the EM drive, the electromagnetic drive, a reactionless thruster that operates only on RF energy. It supposedly violates the laws of conservation of momentum, but multiple independent lab tests have shown that it produces thrust. What’s the real story? That’s a little more complicated.
The EM Drive is a device that turns RF energy — radio waves — directly into thrust. This has obvious applications for spacecraft, enabling vacations on Mars, manned explorations of Saturn, and serious consideration of human colonization of other solar systems. The EM drive, if proven successful, would be one of the greatest inventions of all time. Despite the amazing amount of innovation the EM drive would enable, it’s actually a fairly simple device, and something that can be built out of a few copper sheets.