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    RC Battery Guide: The Basics of Lithium-Polymer Batteries

    With appealing attributes such as low weight, high energy density, and ever greater discharge rates, Lithium-Polymer (LiPo) batteries have transformed all facets of RC. The emergence and continual improvement of these batteries has provided a significant performance boost for RC cars, boats, airplanes, and helicopters, while also paving the way for new vehicles such as multi-rotors. All of this electric goodness does not come without a cost. If not handled and utilized properly, LiPo batteries can quickly become damaged or even catch on fire. Today, I'm sharing some of the basic things you should know about making the most of LiPo batteries. I will also provide techniques to mitigate the risks that these batteries pose.


    Understanding the LiPo Lingo

    When talking about a LiPo, the primary characteristics to understand are the battery’s voltage and capacity. This is typically noted in a shorthand such as “4S-2200”. In this example, “4S” denotes that the battery has four cells in series. The nominal voltage of each cell is 3.7 volts (4.2v fully-charged), so the total pack voltage is:

    4 cells x 3.7v = 14.8v.

    When talking about a LiPo battery, the primary characteristics to understand are the battery’s voltage, capacity, and discharge rate.

    The second number denotes the capacity of the battery in milliamp-hours (mAh). A fully charged 2200mAh pack is rated to provide a current of 2200 milliamps (2.2 amps) for one hour before it is fully discharged. This capacity value is completely independent of how many cells are in series. In simple terms, the capacity value allows you to estimate how long a battery will provide useful power in a given application. In practical terms for RC use, the capacity rating is typically only helpful for rough comparisons of different batteries. i.e. a 2S-5000 battery will provide about double the run time of a 2S-2500 lipo in the same RC car.

    While it was quite common 10 years ago, is now rare to find a RC LiPo battery that uses cells in parallel. Let’s look at an example in case you happen across one. A 4S2P-2200 battery would consist of two 4S-1100 batteries wired in parallel to provide a total 2200mAh capacity. All other things being equal, you would care for and use this battery the same as you would the previous 4S-2200 example (which is really a 4S1P-2200, but we ignore the 1P). There may be a difference in physical size, but a 4S-2200 and a 4S2P-2200 are functionally equivalent. The differences will really only matter to the guy at the factory who has to assemble the battery.

    The Smart Highway Project Prototype

    Vice Motherboard interviews designer Daan Roosegaarde about his collaboration with a Dutch construction company to implement a Smart Highway prototype in the Netherlands. The project is actually a set of 20 systems to assist drivers and tap into the potential of electric cars, including inductive charging lanes and contextually illuminated roads. Read more about Smart Highway here.

    SteamVR (HTC Vive) Prototype Hands-On + Impressions

    We test the most talked about virtual reality demo at this year's Game Developers Conference: Valve's SteamVR prototype. Made in collaboration with HTC, the Vive VR headset will be released later this year and features an incredible positional tracking system. We chat with Valve's engineers about the technology in the headset and share our demo impressions. This is the real deal.

    In Brief: More Details on Sony's New Morpheus Prototype

    At Sony's GDC press conference, the company announced and showed off a second public prototype of its Project Morpheus virtual reality headset, which will ship to consumers in the first half of next year. The PlayStation 4 accessory now uses a 5.7-inch 1080p OLED display with an RGB subpixel arrangement, running at 120Hz. That's a big upgrade from the 60Hz LCD panel we saw in last year's prototype, and 120Hz should allow for low persistence. While 120FPS is the target framerate for the device, developers will be angle to render at 60Hz and output to the HMD at 120Hz. The PS4 uses HDMI 1.4, which can drive 1080p at 120Hz, but not 1440p at that refresh rate. Field of view is listed at 100 degrees, and positional head tracking is assisted by nine IR LEDs. Sony says that latency is under 18ms, which they claim is good enough for the sensation of presence. We'll be trying the new prototype and the four demos built for it at the GDC show floor tomorrow.

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    A Brief History of Net Neutrality

    Short and to-the-point primer about the history of net neutrality from The Verge: "In the wake of net neutrality's victory, we look back at the history of its fight in this visual history explainer." For more reading about the history of the fight for net neutrality, visit the Electronic Frontier Foundation's landing page on the topic. (Support those electrons!)

    RC Transmitter Guide: The Basics of Computer Radio Systems

    Once the RC bug has bitten and you know that you’ll be in the hobby for a while, buying a good quality computer radio system is one of the best investments that you can make. These radios have onboard processors that enrich them with many features not usually found on “dumb” units. The benefits of some of these features are self-evident, such as the ability to use the same transmitter for multiple models. Other features found on computer radios are a bit tougher to grasp. Consequently, many modelers simply ignore them—and forfeit some very useful capabilities.


    Today, I will cover a few of the basic features that are afforded by computer transmitters: what they are and how/when they are helpful. I won’t be covering any specifics on how to program these features on your particular radio--that’s what the owner’s manual is for. My focus will be on radios for aircraft, but surface computer radios (for cars and boats) share many of the same features!

    How Many Channels Do You Need?

    Most computer radio systems have six or more channels, with 6-channel models being very popular among rookie hobbyists. Up until recently, I would have endorsed that decision. Now I suggest going with no less than seven channels – preferably eight. The reason for my change of heart is that the average flying model is evolving into an ever more complex machine.


    Powered aircraft need no more than four channels to fly (pitch, roll, yaw, & throttle). Additional operations (retractable landing gear, flaps, lost model alarms, lighting systems, sound systems, gimbals, gyros, bomb releases, etc.) are becoming much more prevalent in off-the-shelf models, and they require additional channels to make them function. These add-ons aren’t necessary to fly, but they sure are fun. So why should your radio keep you from enjoying them? I know several flyers who initially purchased a 6-channel radio, only to upgrade a few months later. Consider where your RC interests might lead and invest in a radio that will accommodate those needs.

    In Brief: The First Demo of Magic Leap's Augmented Reality Technology

    Microsoft's HoloLens may be the first headset to bring augmented reality to the masses, but Magic Leap's technology may be more interesting. The secretive startup's product--which we've only been able to speculate on with inferences and patent filings--gave its first demo to press for an MIT Technology Review profile. The impressions indicates that Magic Leap's AR display will be more akin to Avegant's DLP-based retinal display than a projected image reflected on glass, as is expected in HoloLens (and Google Glass). The whole report is worth a read.

    What You Should Know about FAA’s Proposed Drone Rules

    Drones, quadcopters, multi-rotors…call them what you wish. The Federal Aviation Administration (FAA) prefers the term sUAS (small Unmanned Aerial Systems). As businesses anxious to use the technology have been awaiting guidance from the FAA on what will be legal practice, the agency’s actions have hinted that they intended to rule commercial sUAS users with an iron fist. In response, the drone industry and its advocates have been circling the wagons in preparation for a looming battle against the FAA.

    Even under recent congressional pressure, FAA personnel refused to indicate when they would release their sUAS rules. It therefore came as a surprise when the FAA suddenly announced a media conference call to unveil the details of their sUAS Notice of Proposed Rulemaking (NPRM). That the call was hastily set for Sunday on a holiday weekend only stoked fears that the government’s hammer was about to fall. Yet, when the FAA laid their cards on the table, drone enthusiasts had more to praise than to complain about.

    Cliff Whitney is the owner of Atlanta Hobby, one of the busiest multi-rotor dealers and repair shops in the country. In a phone interview following the FAA announcement, Whitney said “The proposal got a lot of things right. The FAA has obviously been listening to the feedback people have been giving them.”

    Visual line-of-sight (VLOS) must be maintained at all times!

    Multi-rotor manufacturers are breathing a sigh of relief as well. Jon Resnick, a policy and marketing representative for DJI, echoed a common response seen all across the internet, “Overall, while it's not perfect, the proposal is far less onerous than many of us expected.”

    The FAA’s proposal is just that--an offering. It will take some time before actual laws are in the books. The proposal will first be published to the Federal Register, where it will be open to public comment for 60 days. The FAA will then need some time to review the comments and incorporate any changes. Optimists estimate that we could see the proposal become law as soon as late 2015. Until then, here's how we feel about the specifics of the proposal.

    The Best Smartwatch (For Now)

    This post was done in partnership with The Wirecutter, a list of the best technology to buy. Read the full article below at TheWirecutter.com

    A good smartwatch connects to your smartphone, but it actually untethers you from nervously checking that phone. The smartwatch (for now) that best augments your Android or iPhone, and looks good doing it, is the Pebble Steel.

    After more than 40 hours of research, wearing and comparing nine smartwatches, and keeping a close eye on battery life and Bluetooth connections, we found the Pebble Steel to be the most adaptable watch for most wrists and lifestyles. Its battery lasts nearly an entire work-week—the longest of any we tested—it has the most useful apps, and it holds up to abuse.

    How we decided what to test

    We tested smartwatches primarily on how they did their main job: showing notifications from your phone, and controlling a few parts of it. We also put a good deal of weight on the visibility of the screen, the interface of the watch, and the ability to keep running all day.

    But looks matter, too, when you wear something every day. The size, heft, and visual appeal of each watch was considered, as well as its bands and clasps. We fastened our smartwatches on many friends' wrists, male and female. And we considered the external experience with each watch: the connection-managing app that came with every watch, the charging dock and cable, and the third-party apps and tools compatible with each watch. Our full guide has more details on what we did to narrow down the field and test smartwatches.

    Experimenting with Fluid Assembly Furniture

    The latest from MIT's Self-Assembly Lab: "Fluid Assembly is part of a series of investigations by MIT’s Self-Assembly Lab looking at autonomous assembly in complex and uncontrolled environments (water, air, space etc). In this experiment a number of components are released into a tank of turbulent water. Each of the components is completely unique from one another and has a precise location in the final structure. The process was filmed over 7 hours, after which a full assembled, precise chair was created." More details on this project here. (h/t Wired)

    In Brief: Sony Releases Its SmartEyeGlass Developer Kit

    Sony is making available the first developer kits for its SmartEyeGlass initiative, with the hopes that developers will make apps for it ahead of a commercial release. The glasses connect to an Android smartphone and integrate numerous sensors to display data in the wearer's line of sight, via a monochrome translucent display. This isn't the SmartEyeGlass Attach prototype we tried on at CES, but the version that debuted in late 2014. That Attach prototype had potential for consumer use, but the glasses available today are for industrial applications. Given our experiences with the Google Glass Explorer's Edition, we're unlikely to be purchasing this developer's kit for testing. But I'm curious to see what the response will be and what kind of apps the devs who do purchase it will make.

    CoeLux Artificial Skylight Mimics Sunlight

    Unveiled at a lighting conference late last year, CoeLux is a lighting system that simulates a natural light through a skylight. And based on initial impressions and photographs, it's a convincing representation of the kind of scattered natural light you would see through a window. The artificial skylight will cost over $65,000 to install, and the current product consumes a whopping 340W of power. The next versions will bring power consumption and cost down with the use of LEDs, and CoeLux is also looking to allow users to adjust color temperature (golden hour on command!) and the angle of illumination. This is awesome and scary technology; the photography implications are exciting, but I can't help but imagine how it'll affect the design of dense high-rises (and prison cells) of the future. (h/t Petapixel)

    10 Tracking Technologies You Should Know About

    “Big Brother,” the surveillance state posited by George Orwell in his prescient novel 1984, was a fantasy at the time. But now it seems all too real. Just about every piece of technology you interact with has the ability to monitor you in some way and transmit that information to the government or private entities. Here’s a quick rundown of the latest tracking tech to be aware of.

    Hands-on with Sony's $1100 Walkman NW-ZX2

    Sony recently unveiled a new Walkman music player, which plays what they call "high resolution" audio. The noisy booth at CES probably wasn't the best place to demo this $1100 player, but we try it out and ask a Sony rep just why they think audiophiles should buy in to Sony's new music playback ecosystem. (This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)

    Why I’m Excited About Windows Holographic

    My absolute favorite part of covering technology for Tested are those rare glimpses of the future. I’m talking about the first hints of a new technology that has a chance to change the world. That's why we started experimenting with 3D printers and tablets shortly after we launched Tested in 2010. That's why we were among the first people to get excited about the latest wave of virtual reality and the rise of cheap multi-rotors. It's why we're investigating potentially revolutionary last-mile travel solutions, like the Boosted Board and Rocket Skates. To me, technology is most interesting when it's brand new, before designers have chamfered the rough edges and the revolutionary leaps have made way for incremental improvements. I love it when I look at a tech demo and can still see the path that led to the creation of a new product or even a new category.

    Each of the example technologies that I mentioned above was the result of multiple advancements being assembled by visionaries at the right time. The decreased cost of LCD screens, flash memory, and high capacity, low-volume batteries made modern smartphones possible. The popularity of smartphones caused the price of the components found within them--solid state accelerometers and gyroscopes, LCD displays, and processors--to drop until technologies like VR suddenly became possible at much lower prices than we ever imagined. Likewise, the rise of low-cost, high-power microcontrollers (Arduino boards and their ilk), combined with inexpensive motors and radios and cheap manufacturing in China caused revolutions in multirotor aircraft and 3D printing.

    These categories are all transforming from hyper-expensive products designed to serve tiny niche markets into mainstream consumer electronics. The people responsible for these innovations have one thing in common. They were able to see the pieces necessary and assemble them into workable products before anyone else saw the same potential. This is what Palmer Luckey did for VR with the early Oculus prototypes and what the originators of the Reprap project did for consumer 3D printing.

    This brings us to Microsoft's Windows Holographic, which Microsoft demoed at a Windows 10 event yesterday. Despite its wildly misleading name (from what I can tell Holographic doesn't use holograms at all), Microsoft's demo showed augmented reality, seemingly working in the real world, with fewer caveats than anything we've seen before.

    If you aren't familiar with AR, it's similar to virtual reality in that it displays information from a computer over your full field of vision. However, where VR is an isolated experience, you put the goggles on and they block your view of the outside world, AR overlays that information on the environment your in. Put another way, VR replaces the world around you, AR enhances it.

    CES 2015: Quadcopter Combat with "Game of Drones"

    Will and Norm battle in the desert with quadcopters--or at least do their best--at a Game of Drones event during CES. We learn about the rules of safe quadcopter combat and chat with Game of Drones' founder to discuss the reasons for building a more durable quadcopter airframe. (This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)

    CES 2015: Parrot's eXom Aerial Mapping Quadcopter

    In the quadcopter space, Parrot may be best known for its AR.Drone and mini quads, but they're also behind two initiatives to use unmanned vehicles for aerial mapping. SenseFly and Pix4D are two departments making those vehicles and the 3D mapping software, and we learn about their latest quad at this year's CES. (This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)

    CES 2015: Hands-On with the Avegant Glyph Prototype

    Head-mounted displays have received a lot of attention for their potential use as virtual reality devices, but most are still LCD or OLED panels strapped to your head. We saw Avegant's "virtual retinal display" prototype last year--a HMD that uses DLP mirrors to project images directly into your eyes. Checking in with Avegant at CES, we look at their latest prototype chat with them about their final product plans. (This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)

    CES 2015: Test Riding the Acton RocketSkates

    Here's something we didn't expect to test at CES. Acton's RocketSkates was a Kickstarted invention to put electric motorized wheels on your shoes. Will puts on a pair of these futuristic skates to try to learn how to move around in them, and then chats with its inventor to learn how this idea came about. (This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)

    CES 2015: Hands-On with Sony's SmartEyeGlass Prototype

    Google Glass may no longer be available to buy, but Sony is working on an augmented reality accessory that may have similar features. We get to put on the SmartEyeGlass Attach prototype at this year's CES, at least to see how its display looks over your field of view. Too bad the representative that we were allowed to speak to on camera wasn't able to give us many concrete details...(This video was shot with a Sony PXW-X70 camera, which we're testing. Thanks to B&H for providing us with gear for CES!)