At Last, (Almost) A Cellphone With No Batteries!

If you are tired of constantly having to worry about the state of the battery in your mobile phone, then maybe help is at hand courtesy of the University of Washington. They are reporting the first-ever battery free cell phone, able to make calls by scavenging ambient power. An impressive achievement, and one about which we’d all like to know more.

On closer examination though, the story is revealed as not quite what it claims to be. It’s still a very impressive achievement, but instead of a cell phone with which you can make calls through the public cell network, it’s more of a remote handset for a custom base station through which it can place Skype calls. Sadly the paper itself is hidden behind a journal publisher’s paywall, so we’re left to poke underneath the research group’s slightly baffling decision to use the word “Cellphone” for something that plainly isn’t, and the university PR department’s dumbing-down for the masses. Aren’t peer reviewers supposed to catch misleading descriptions as well as dodgy science?

In radio terms, it’s an analog AM two-way radio that uses a backscatter transmission technique of applying the modulation as switching to an absorbing antenna tuned to the RF source whose ambient energy is being utilized. This modulates the ambient field within the range of the device, and resulting modulated field can be received and demodulated like any other radio signal. It’s a simplex device, in that you can’t listen and talk at the same time. Other ambient power used by the circuitry is harvested by rectifying received RF and through capturing ambient light on a set of photodiodes. There is a short video explaining the system, which we’ve placed below the break.

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Hackaday Links: July 9, 2017

Doom is now running on the ESP32. This is some work from [Sprite_tm], and the last we heard about Doom on the ESP32 is that there was a silicon bug or something. Now we’re knee deep in the dead on a tiny WiFi and Bluetooth-enabled microcontroller.

Loading animations have a long and storied history. What originally began as an hourglass quickly turned into a hand counting to five and progress bars. There were clocks, the Great Beach Ball of Death, and now loading animations are everywhere. However, the loading animation has still not been perfected — until now, that is. This is a fidget spinner loading animation. It’s beautiful.

Just a quick reminder that a Minecraft scholarship exists. Yeah, I know what you’re thinking, but there is a scholarship from the Klingon Language Institute for studying any language, and last year’s winner built a redstone computer from scratch,

[8bit generation] recently released a documentary, about the rise of Atari. Easy to Learn, Hard to Master is about the rise of Atari under [Nolan Bushnell]. Now [8bit generation] is working on a new documentary: Firing Steve Jobs. The [Steve Jobs] story is fascinating, and no matter what you think of him, he probably knew what he was doing.

Want to build and sell some hardware? Over on Tindie, we’re taking a look at some of the most successful designers of custom crafted hardware. This time it’s [Albertas Mickėnas] of Catnip Electronics who has sold five thousand soil moisture sensors.

You can just go out and buy a CNC machine, but that doesn’t quite underscore the difficulty in getting a CNC machine running. Our ‘ol pal [Jeremy] recently picked up a Romaxx CNC machine and put together a video of its commissioning. There’s a lot of work here, from building a shelf/stand for a rather beefy machine to cutting into the bed for t-tracks, and figuring out how dust collection is going to happen.

Before there was KiCad and Eagle and a ton of web-based PCB design tools, there was Autotrax. Want to know what PCB design and GUIs look like in DOS? I did a walkthrough for designing a small PCB in the DOS version of Autotrax late last year. There are thousands of designs locked up in discontinued EDA suites, and [Erich] has a way to revive them. He’s developed an Autotrax/Easytrax layout import/export plugin for pcb-nd. Now legacy Protel designs can be imported into software released in this century. This is really cool, and you can check out some screenshots here.

Hacking Touch Screens to Count Pulses

Heart rate sensors available for DIY use employ photoplethysmography which illuminates the skin and measures changes in light absorption. These sensors are cheap, however, the circuitry required to interface them to other devices is not. [Petteri Hyvärinen] is successfully investigating the use of capacitive touchscreens for heart rate sensing among other applications.

The capacitive sensor layer on modern-day devices has a grid of elements to detect touch. Typically there is an interfacing IC that translates the detected touches into filtered digital numbers that can be used by higher level applications. [optisimon] first figured out a way to obtain the raw data from a touch screen. [Petteri Hyvärinen] takes the next step by using a Python script to detect time variations in the data obtained. The refresh rate of the FT5x06 interface is adequate and the data is sent via an Arduino in 35-second chunks to the PC over a UART. The variations in the signal are very small, however, by averaging and then using the autocorrelation function, the signal was positively identified as a pulse.

A number of applications could benefit from this technique if the result can be replicated on other devices. Older devices could possibly be recycled to become low-cost medical equipment at a fraction of the cost. There is also the IoT side of things where the heart-rate response to media such as news, social media and videos could be used to classify content.

Check out our take on the original hack for capacitive touch imaging as well as using a piezoelectric sensor for the same application.

Hackaday Prize Entry: Watching Out for Forest Fires

Hackaday Prize entrant [Danie Copnradie] lives in South Africa where wildfires are a major problem. Every year, humans and animals are killed, crops are destroyed, and property is lost. The FireBreakNet project aims to deploy wireless environmental sensors that alert farmers, park rangers, and emergency personnel when fires break out.

According to [Danie], firefighting services are underfunded in South Africa, with farmers and their employees having to do a lot of the work involved in firefighting with their own equipment. Having access to a network of early warning sensors would allow for faster response times, saving money and lives.

The goals of the project include a low price, easy deployment, low power consumption, physical ruggedness, and scalability. Currently, [Danie] is testing Adafruit Feather as well as Texas Instruments LaunchPad for the brains of each node, taking readings from CO2 and temperature sensors, optical air quality sensors as well as optical flame sensors.

Making a Small-Scale Brewery With A Raspberry Pi And Python

No doubt many Hackaday readers will have tried their hand at home brewing. It’s easy enough, you can start with a can of hopped malt extract and a bag of sugar in a large bucket in your kitchen and achieve a decent enough result. Of course, once you get the taste it’s a field of infinite possibilities, so many enthusiasts go further into the realm of beer making with specialty ingredients and carefully controlled mash tuns.

Such an inductee into the brewery arts is [Christopher Aedo], who has documented his automated brewing system driven by a Raspberry Pi running CraftBeerPi. And it’s an impressive setup, with boil kettle, mash tun, and heat exchanger, a 5KW heating element, and all associated valves, pipes, pumps, and sensors. This ensures consistency and fine control over temperature over the long-term at all stages of the brew, something that would be very difficult to achieve manually at this scale.

The whole brewery is mounted on a cart for portability and has been used for a lot of brew cycles of many different styles. We can’t help a touch of envy at the array of beer taps in his kitchen.

Over the years we’ve brought you a few brewing projects. Another Pi-based setup graced these pages in 2012, as did a brewery using a Lego Mindstorms controller. Top marks go though to the brewer who fought his beer belly through brewing machinery powered by an exercise bike.

Via Recantha.

ISM Communications for Arduino

If you want to wirelessly communicate between devices, WiFi and Bluetooth are obvious choices. But there’s also the ISM (industrial, scientific, and medical) band that you use. There are inexpensive modules like the SX1278 that can handle this for you using LoRa modulation, but they haven’t been handy to use with an Arduino. [Jan] noticed the same thing and set out to build a shield that allowed an Arduino to communicate using LoRa. You can find the design data on GitHub. [Jan] calls it the LoRenz shield.

According to [Jan], the boards cost about $20 to $30 each to make, and most of that cost was in having PC boards shipped. LoRa lets you trade data rate for bandwidth, but typical data rates are fairly modest. As for range, that depends on a lot of factors, too, but we’ve seen ranges quoted in terms of miles.

Depending on where you live, there may be legal restrictions on how you use a radio like the SX1278. You should understand your local laws before you buy into using the ISM bands. We aren’t sure it would be wise, but the board can coexist with three other similar shields. So you could get 4 radios going on one Arduino if you had too and could manage the power, RF, and other issues involved. The breakout board the module uses has an antenna connector, so depending on your local laws, you could get a good bit of range out of one of these.

[Jan] promises a post on the library that makes it all work shortly, but you can find the code on GitHub now. If you look at the code in the examples directory, it seems pretty easy. You’d have to sling some software, but the SX1278 can support other modes in addition to LoRA including FSK and other data modulation techniques.

We’ve seen other LoRa shields, but not many. If you are interested in other wireless technologies, we’ve talked about them quite a bit. If you want a basic introduction to LoRa, [Andreas Spiess’] video below is a good place to start.

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A Poor-Man’s Laser CNC Engraver

What do you get when you mix the disappointment that sometimes accompanies cheap Chinese electronics with the childhood fascination of torturing insects with a magnifying glass on a sunny day? You get a solar-powered CNC etcher, that’s what.

We all remember the days of focussing the sun on a hapless insect, or perhaps less sadistically on a green plastic army man or just a hunk of dry wood. The wonder that accompanied that intense white spot instantly charring the wood and releasing wisps of smoke stayed with you forever, as seemingly did the green spots in your vision. [drum303] remembered those days and used them to assuage his buyer’s remorse when the laser module on his brand new CNC engraver crapped out after the first 10 minutes. A cheap magnifying glass mounted to the laser holder and a sunny day, and he don’t need no stinkin’ lasers! The speed needs to be set to a super slow — 100mm per minute — and there’s the problem of tracking the sun, but the results are far finer than any of our childhood solar-artistic attempts ever were.

Do we have the makings of a possible performance art piece here? A large outdoor gantry with a big Fresnel lens that could etch a design onto a large piece of plywood would be a pretty boss beachside attraction. Of course, you’d need a simple solar tracker to keep things in focus.

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