Two-Axis Solar Tracker

August 25, 2015 by Bryan Cockfield 32 Comments

Solar panels are an amazing piece of engineering, but without exactly the right conditions they can be pretty fickle. One of the most important conditions is that the panel be pointed at the sun, and precise aiming of the panel can be done with a solar tracker. Solar trackers can improve the energy harvesting ability of a solar panel by a substantial margin, and now [Jay] has a two-axis tracker that is also portable.

The core of the project is a Raspberry Pi, chosen after [Jay] found that an Arduino didn’t have enough memory for all of the functionality that he wanted. The Pi and the motor control electronics were stuffed into a Pelican case for weatherproofing. The actual solar tracking is done entirely in software, only requiring a latitude and longitude in order to know where the sun is. This is much easier (and cheaper) than relying on GPS or an optical system for information about the location of the sun.

Be sure to check out the video below of the solar tracker in action. Even without the panel (or the sun, for that matter) the tracker is able to precisely locate the panel for maximum energy efficiency. And, if you’d like to get even MORE power from your solar panel, you should check out a maximum power point tracking system as well.

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100 Semifinalists For The 2015 Hackaday Prize

August 24, 2015 by Mike Szczys 26 Comments

Entries for the 2015 Hackaday Prize — the nine-month design contest that challenges you to build something that matters — closed one week ago today. There were over 900 entries and everyone at Hackaday has been blown away by the different approaches used to solve problems affecting a large number of people, and at the huge body of Open Hardware that has been documented by the process.

Today it is our pleasure to announce the 100 Semifinalists who will move on to the next round. Congratulations to you all on this accomplishment. These designs will continue to be refined as we approach the September 21st deadline where 10 finalists will be chosen by our expert judging panel: Akiba, Pete Dokter, Lenore Edman, Limor Fried, Jack Ganssle, Dave Jones, Heather Knight, Ben Krasnow, Ian Lesnet, Windell Oskay, Micah Scott, and Elecia White. The 10 finalists will go on to compete for the Grand Prize: A Trip into Space or $196,883.

For those who didn’t move on to the Semifinal round, please do not take this as a strike against your work. Don’t stop now, your ideas can still change the world!

Best Product finalists were announced in this post.

Browse the 2015 Semifinalists List or the full list of entries.

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Hackaday Prize Entry: Feral Cats Phone Home With Das Katzetelegraf

August 23, 2015 by Dan Maloney 41 Comments

Feral cats are a huge problem in some areas. Roaming freely in cities and in rural settings and reproducing with reckless abandon, colonies of feral cats can exhibit nuisance behavior that often results in unpleasant measures being taken to control their population. More humane programs, such as trap-neuter-return (TNR), seek to safely trap cats, give them basic vaccinations and neuter them, and either return them to their colony or, for a lucky few, ready them for adoption. Such programs are proving successful, but are not without issues. Enter Das Katzetelegraf.

You don’t need to understand a lick of German to figure out exactly what Das Katzetelegraf does from its name. Consisting of an Arduino, a GSM module, and a simple magnetic reed switch attached to the door of a humane cat trap, Das Katzetelegraf sends a text message to a TNR program volunteer when a cat has been trapped. Instead of waiting in the trap for the TNR workers to make daily rounds, the cats are quickly retrieved and the trap is reset for the next cycle. This reduces the time the cat spends in the trap, stressed and without access to food or water, and improves the animal’s outcome. As a bonus, each trap’s throughput is increased, so more animals can be cycled through the TNR program.

TNR can really help reduce feral cat populations, and Das Katzetelegraf can make them even more effective. But if you just have a stray cat pooping up your garden, a Raspberry Pi cat-deterring sprinkler might be a better choice.

The 2015 Hackaday Prize is sponsored by:

Hackaday Prize Entry: Twitter Goes To The Dogs With Raspberry Pi Hack

August 21, 2015 by Richard Baguley 7 Comments

Dogs are remarkable creatures. Anybody who has lived with one will know that they are very vocal beasts, with barks that range from noting the presence of a squirrel in the yard to the warning whine that says “I am about to pee on your shoes if you don’t take me outside.” [Henry Conklin] decided to computerize the analysis of these noises, putting his dog [Oliver Twitch] on Twitter so he could hear what he was saying while he was at work. [Henry] that is: [Oliver] stays at home.

He did this using a Raspberry Pi, which is set to record sound above a certain volume. With the system sitting by [Oliver’s] favorite window, this records his barks. The recordings are then analyzed using PyAudioAnalysis, a library that analyzes sounds, compares them to reference ones and classifies them. The Raspberry Pi then posts the results onto twitter using Python-twitter.

The setup used by [Oliver] to capture the barks: a USB microphone, Raspberry Pi and WiFi USB dongle.

Or rather, it will when [Henry] fixes a few bugs: right now it just posts a random string that is based on the length of the bark, not the type. [Henry] says he is working on the dog translation at the moment. It’s still a neat project that shows you how simple it is to use a few small bits of code to gather info from your environment and share these over the Internet. [Henry] also says that the next step is creating a weekly podcast for [Oliver]. I, for one, will be subscribing to hear his thoughts on how annoying the postman is, and how vexing it is to see a squirrel and not be able to chase them.

The 2015 Hackaday Prize is sponsored by:

Hackaday Prize Entry: Lighting The Way For Walkers

August 20, 2015 by James Hobson 8 Comments

Chances are, you probably know someone who uses a walker to assist in their mobility. Ever wonder about how they could be made better? When [Alan McFarland] noticed his friend using his iPhone as a light to walk down a hallway — with only one hand on his walker — he realized something could easily be done to make the walker more functional. His own light bar.

Sure you could get a flashlight, zip tie it to the walker, or maybe a bike light with a dedicated mount — but [Alan] wanted it to be a bit more elegant; and functional. With this in mind, he attached an LED light strip to the lower frame of the walker to help illuminate the path ahead. A button is wired up to the handle for easy access, and he’s even using a PIC12F1501 microcontroller to give it some logic — it’ll turn off by itself, fading out, giving the person a chance to sit down before the lights go out.

The thing we like about this project is he programmed it using the PICBASIC PRO compiler — the same compiler that [Alan] himself used nearly 20 years ago programming the Borg suits and spacesuit lighting on Star Trek: First Contact — how’s that for a random trivia fact!

The 2015 Hackaday Prize is sponsored by:

Hackaday Prize Entry: Open-source Pulse Oximetry

August 19, 2015 by Dan Maloney 9 Comments

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:

Hackaday Prize Entry: The 70s Called. They Want This Calculator

August 18, 2015 by Bryan Cockfield 32 Comments

For those of us who grew up during TI’s calculator revolution, the concept of reverse polish notation (RPN) might be foreign. For other more worldly calculator users, however, the HP calculator was ubiquitous. Hewlett-Packard peaked (at least as far as calculators are concerned) decades ago and the market has remained dominated by TI since. Lucky for those few holdouts there is now a new microcode emulator of these classic calculators.

Called the NP25 (for Nonpariel Physical), the calculator fully emulates the HP-21, HP-25C and HP-33C. It’s a standalone microcode emulator, which means that these calculators work exactly as well as the original HP calculators of the 70s did. The new calculators, however, are powered by a low power MSP430G2553 processor and presumably uses many, many fewer batteries than the original did. It has an LED display to cut power costs as well, and was built with the goal of being buildable by the average electronics hobbyist.

Even if you didn’t grow up in the 70s with one of these in your desk drawer, it’d still be a great project and would help even the most avid TI user appreciate the fact that you don’t have to use RPN to input data into calculators anymore. Not that there’s anything wrong with that. This isn’t the only calculator we’ve featured here, either, so be sure to check out another free and open calculator for other calculator-based ideas.

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