Sniffing pH Sensor RF Signals for Feedback Re: Your Esophagus

For about a week [Justin] had a wireless acidity level sensor in his esophagus and a pager-looking RF receiver in his pocket. So he naturally decided to use an RTL-SDR dongle to sniff the signals coming out of him. As most of our Hackaday readers know, these cheap RTL2382U-based DVB-T receivers are very handy when it comes to listening to anything between 50MHz and 1800MHz. [Justin] actually did a great job at listing all the things these receivers can be used for (aircraft traffic monitoring, weather images download, electric meter reading, pacemaker monitoring…).

After some Googling he managed to find his Bravo pH sensor user’s guide and therefore discovered its main frequency and modulation scheme (433.92MHz / ASK). [Justin] then used gqrx and Audacity to manually decode the packets before writing a browser-based tool which uses an audio file. Finally, a few additional hours of thinking allowed him to extract his dear esophagus’ pH value.

Designing a WakeUp Light

[Akhil] and his wife recently finished their WakeUp Light project. As the name suggests, this kind of morning alarm uses light to wake you up in the morning. The main constraints when starting this relationship-strengthening adventure were cost, ability to work with any table lamp, and having a simple but effective control interface, all while keeping all the design open. The created platform (put in the wooden box shown above) is built around a Stellaris Launchpad (ARM Cortex M4 based) and uses an AC dimmer circuit found in this instructable. For our readers interested in those, [Akhil] mentions two very interesting articles about their theory of operation here and here.

An Android application has been made to set up all the alarm parameters, which uses the phone’s Bluetooth to communicate with the (well-known) HC-05 Bluetooth transceiver connected to the Launchpad. For safety, the current design also includes an LM4876 based audio amplifier connected to the microcontroller’s PWM output. The next revision will integrate a Digital to Analog Converter and an SD-Card slot for better quality and music diversity. A presentation video is embedded after the break and you can find the official repository at GitHub.

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Measuring Poop for a Better Sanitation Service

poop

Hacking can make a huge difference in peoples’ lives. So when the Nottingham Hackerspace was challenged with optimizing Ugandan Toilets, they hopped on-board.

Back in January of this year [Nicola Greene] approached the hackerspace with this real-life design problem. She represents Water for People, with support from a UK-based Engineers Without Borders organization. Water for People is involved with improving access to sanitation in Uganda and many other third world countries — to make sure everyone has access to a safe and usable toilet. The cool thing with Water for People is they don’t just want to build an infrastructure for the people and run away, they want to bring together local entrepreneurs and the community to establish a system that will actually last.

So, what is the problem anyway? Well, since Uganda doesn’t have quite the same network of sanitation businesses as we might, it’s important for the new infrastructure to know a few things — in particular, how much do we poop? This question was summarized into a basic goal for the Nottingham Hackerspace:

To develop a low-cost (<$200) monitoring device to give an approximation of what volume of liquids — and in an ideal world, solids, is entering the latrine.

Before you click through, think about how you would solve this?

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Billboard Advertises Engineering School, Manufactures Potable Water

It’s a remarkable thing when ad agencies manage to help people in the course of advertising. The University of Technology and Engineering Peru (UTEC) was looking for ways to increase enrollment. They went to the Peruvian offices of agency DraftFCB and came away with the idea to install a billboard that converts Lima’s water-saturated coastal desert air into potable water.

Perhaps the only downside is that it requires electricity, and not just for those cool neon water drops. There are five generators that capture the humidity and use reverse osmosis to purify the water. Each of these units has a tank that holds 20L. From there, the clean water is aggregated in a main tank and can be collected from a faucet at the base of the billboard. In just three months, the billboard produced over 9,000L (2500 gallons) of potable water for people who would otherwise draw polluted water from wells.

We love to see hacks that help. Use your powers for good, like re-purposing humid air and pollution. Make the jump to see a short video and an artist’s conception of the billboard’s innards.

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Gritz: An Open Source Speed Reading Tool

Here’s a hack to help you increase your reading speed. Gritz is an open source text file reader, which reduces the need to look around the screen. Words pop up one at a time, but at a configurable pace.

[Peter Feuerer] got the idea for Gritz from Spritz, a commercial product for speed reading. The creators of Spritz took three years to develop their software, and recently released a demo. They claim people can read at 1000 WPM using this technology. Spritz is taking applications for access to their APIs, which will allow developers to integrate the software into their own applications. However, a fully open source version with no restrictions would be even better.

Using Gritz, [Peter] claims to have read a book with a 75% improvement in his reading speed. He admits it’s not perfect, and there’s still much development to do. Gritz is written in Perl, uses Gtk2 for its GUI, and comes with instructions for running on Linux, OS X, and Windows. It’s released under the GPL, so you can clone the Github repo and start playing around with accelerated reading.

This Desktop Air Conditioner Is Really Cool!

[Mike] works in a 50+ year old building with unreliable air conditioning. It often reaches 80°F inside during the summer, and he once measured it at 98°F. Rather than burn sick days, he became the envy of the office when he built this awesome desktop air conditioner.

The problem with knocking holes in the office walls and installing window units is that they must vent heat somewhere. [Mike] has overcome adversity and harnessed the power of the heatsink, only in reverse. His desktop a/c unit is made from two 28oz cans plus a 20oz can for the ice bucket. [Mike] used a side-vented CPU fan, which is vital to his design. He secured the heatsink to the base of one 28oz can with a self-tapping screw. This can is the upper chamber. [Mike] made a base from the other 28oz can, drilling holes for the CPU fan wires, the power cord, and a sweet light-up rocker switch. He used Gorilla Glue to affix the CPU fan to the base can.

Hot, stale office air is drawn through the ice in the 20oz can, which is nestled in aluminum foil to maximize heat transfer to the heatsink. The heat in the air gets absorbed by the heatsink, and the CPU fan kicks out cool air in 20-30 seconds.

Hack All the Things in the Time You Save with This LED Pomodoro Timer

Do you want to use your time more productively but are tomato-averse? [Robin]’s LED Pomodoro timer could be the perfect hack for you.

The Pomodoro Technique is a time management solution developed in the late 1980s. The basic idea is to spend a very focused 25 minutes performing some activity such as working or studying and then take a 5-minute break. Many of its proponents use a tomato-shaped kitchen timer to alert them to switch between the two states, but [Robin] wanted to make his own and learn along the way.

First, he wanted to use an ATtiny85 and learn about its features. Specifically, he used its timers, PWM, and low-power sleep mode. [Robin] used Charlieplexing to drive a total of six LEDs. When the timer starts, five yellow LEDs are driven high to indicate each 5-minute slice of work time. A red LED is lit during the 5-minute break.

[Robin] also explored compact PCB design and fabrication. All components are SMD and his board is 4cm square. [Robin] is using this SMD buzzer for discrete feedback. He included a footprint for a six-pin ISP header and programmed it with pogo pins. The timer is completely interrupt-driven: one click of the tactile button starts the work counter, and the buzzer sounds when time is up. A second click starts the break counter.

[Robin] has made everything available in his GitHub repo and encourages you to use it. Time’s a-wastin’!