Body Cardio Weighing Scale Teardown

If you weigh yourself by standing on a bathroom scale, not liking the result, then balancing towards one corner to knock a few pounds off the dial, you are stuck in a previous century. Modern bathroom scales have not only moved from the mechanical to the electronic, they also gather body composition measurements and pack significant computing power.

Yet they’re a piece of domestic electronics that sits in our bathroom and rarely comes under scrutiny. How do they work, and what do they contain? The team at November Five tore down a top-of-the-range Withings Body Cardio scale to find out.

After a struggle with double-sided sticky pads, the scale revealed its secrets: a simple yet accomplished device. There are four load cells and the electrodes for the body measurement, and the PCB. On the board is a 120 MHz ARM Cortex M4 microcontroller, a wireless chipset, battery management, and the analogue measurement chipset. This last is particularly interesting, a Texas Instruments AFE4300, a specialised analogue front-end for this application. It’s a chip most of us will never use, but as always an obscure datasheet is worth a read.

The rather pretty fractal antenna.
The rather pretty fractal antenna.

Finally, the wireless antenna is not the normal simple angular trace you’ll be used to from the likes of ESP8266 boards, but an organic squiggle. It’s a fractal antenna, presumably designed to present a carefully calculated bandwidth to the chipset. A nice touch, though one the consumer will never be aware of.

We’ve shown you quite a few bathroom scales over the years. There was this wisecracking Raspberry Pi scale, this scale reverse engineered to gather weight data, and this one laid bare for use as a controller.

Do You Miss The Sound Of Your Model M?

There is one aspect of desktop computing in which there has been surprisingly little progress over the years. The keyboard you type on today will not be significantly different to the one in front of your predecessor from the 1970s. It may weigh less, its controller may be less power-hungry, and its interface will be different, but the typing experience is substantially identical. Or at least, in theory it will be identical. In fact it might be worse than the older peripheral, because its switches are likely to be more cheaply made.

The famous buckled springs in operation. Shaddim [CC BY-SA 3.0], via Wikimedia Commons.
The famous buckled spring in operation. Shaddim [CC BY-SA 3.0], via Wikimedia Commons.
Thus among keyboard aficionados the prized possessions are not necessarily the latest and greatest, but can often be the input devices of yesteryear. And one of the more famous of these old keyboards is the IBM Model M, a 1984 introduction from the computer behemoth that remains in production to this day. Its famous buckled-spring switches have a very positive action and a unique sound that once heard can never be forgotten.
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Abacus Drive is a Speed-to-Torque Game-Changer

Apart from the harmonic drive, the engineering community hasn’t really come up with any clever mechanisms for speed-to-torque conversion in the last few decades. However, recently a few folks at SRI have given us one more transmission to drool over: the Abacus Drive.

The Abacus Drive takes the standard concepts of a cycloidal drive, but takes the eccentric gear tooth pattern that we’re familiar with and converts it to two grooves in which an array of rolling spacers will ride. The benefit with this design is two-fold: it’s both constructed from entirely rigid components (unlike the harmonic drive), and it has a low-backdriving torque, enabling the application to more easily detect changes in load.

Achieving an affordable low-speed, high-torque transmission has been a holy grail among roboticists, where every motor-driven manipulator joint becomes an engineering design headache where the designers fight their application’s backlash, torque, and price constraints to get a functional robot arm. This problem stems from the fact that motors just don’t perform efficiently at low-speeds, where the near-stall conditions cause them to draw vastly larger amounts of torque compared to their full-speed conditions. While the Abacus Drive isn’t hitting the market anytime soon, we’ll let this idea stew in the community and hope to see some budget variants pop up in the near future.

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Flip Dot Displays Appear with Modernized Drivers

Admit it, you’ve always wanted to have your own flip-dot display to play with. Along with split-flap displays, flip-dots have an addictive look and sound that hearkens back half a century but still feels like modern technology. They use a magnetic coil to actuate each pixel — physical discs painted contrasting colors on either side. It means that you really only need electricity when changing the pixel, and that each pixel makes a satisfyingly unobtrusive click when flipped. The only problem with the displays is that they’re notoriously difficult to get your hands on.

flipdotBreakfast, a Brooklyn-based hardware firm known for creative marketing installations, unveiled their Flip-Disc Display System this morning. Used displays have come up on the usual sites from time to time, but often without a controller. Traditional flip-dot manufacturers haven’t sought out the individual hacker or hackerspace, and a click-to-buy option has been difficult if not impossible to find.

Breakfast’s offering modernizes the driver used to manage all of those electro-mechanical pixels. Whether this will make the displays more accessible is a question that still needs to be answered.
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Build Your Own YouTube Play Button

The only thing that matters in this world is the likes you get on social media platforms. To that end, YouTube has been sending out silver and gold play buttons to their most valuable creators. [Sean] hasn’t screamed into a microphone while playing Minecraft long enough to earn one of these play buttons, so he decided to build his own.

This play button isn’t just a bit of pot metal ensconced in a frame brought to you by Audible dot com; this YouTube play button actually does something useful. It’s a PCB with 144 LEDs working together as a display. There’s an Atmel SAMD21 microcontroller on board to drive the LEDs, and an ESP8266 to pull data down from the Internet. What data is worthy enough to go on an Arduinofied YouTube play button? The subscriber count for [Sean]’s channel, of course. Go subscribe, it might crash his Play button.

Admittedly, there were a few problems with this Play button PCB. Firstly, the ESP8266 can’t directly communicate with the YouTube API to pull down the subscriber count. That problem was fixed with a Raspberry Pi that could connect to the API, and programming the ESP to pull the data from the Pi. Second, this was [Sean]’s first experiment with double-sided SMD boards reflowed in a toaster oven. The first side to be assembled was easy, but to get the second side on, [Sean] turned to low-temp bismuth solder paste. Except for a small error in assembling the board, everything worked as planned.

It’s a great project, and if you want to check out what the better parts of YouTube look like, check out [Sean]’s video below. Don’t forget to rate, comment, like, unlike, or subscribe.

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This Quick Hack Will Keep You Online During Your Next Power Outage

The modern human’s worst nightmare: a power outage. Left without cat memes, Netflix, and — of course — Hackaday, there’s little to do except participate in the temporary anarchy that occurs when left without internet access. Lamenting over expensive and bulky uninterruptible power supplies, Youtube user [Gadget Addict] hacked together a UPS power bank that might just stave off the collapse of order in your household.

This simple and functional hack really amounts to snipping the end off of a USB  power cable. The cable is then attached to a screw terminal to barrel connector adapter and plugged it into a pass-through power USB power bank. No, really — that’s all there is to it. [Gadget Addict] notes that while most modems and routers are designed to run off a 12V power supply, they still operate at 5V. He goes on to connect several router and router/modem combination units to the power bank. In each case the system appears to boot up and perform normally.

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A Smart Wand for all us Muggles

Arthur C. Clarke said that “any sufficiently advanced technology is indistinguishable from magic.” Even though we know that something isn’t “magic”, it’s nice to see how close we can get. [Dofl] and his friends, big fans of the magic in Harry Potter, thought the same thing, and decided to create a magic wand that they could use themselves.

muggle-wand-internalsThe wand itself is 3D printed and has a microcontroller and WiFi board, a voice recognition board, a microphone, and a vibrating motor stuffed inside. The wand converts the voice into commands and since the wand is connected to WiFi, the commands can be used to communicate with your WiFi connected lights (or your WiFi connected anything, really.) Five voice commands are recognized to turn on and off music, the lights, and a “summon” command which is used in the video to request a hamburger from delivery.com. For feedback, the motor is vibrated when a command is recognized.

There’s not much technical information in the original article, but I’m sure our readers could figure out the boards used and could suggest some alternatives to get the wand’s form factor down a bit.  Over the years, other wands have appeared on our pages, using some different technologies.  It’s a fun way to interact with the environment around you, even if you know the “magic” involved is just boring old technology.

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