No, Cat, This Is Not The Litter Box

March 4, 2018 by James Hobson 39 Comments

Hackaday.io user [peterquinn] has encountered a problem with his recently unruly cat peeing under the dining table. Recognizing that the household cat’s natural enemy is the spray bottle, he built an automatic cat sprayer to deter her antics.

The build is clear-cut: an Arduino Uno clone for a brain, an MG995 servo, PIR sensor, spray bottle, and assorted electronics components. [peterquinn] attached the servo to the spray bottle with a hose clamp — ensuring that the zero position is pointing at the trigger — and running a piece of cabling around the trigger that the servo will tug on. Adding a capacitor proved necessary after frying the first Uno clone, as the servo powering up would cause the Uno to reset.

The code is set up to trigger the servo — spraying the cat twice — once the PIR detects the cat for more than ten seconds. After toying with a few options, [peterquinn] is using a 9V, 2A power supply that works just fine. For now, he hopes the auto-sprayer should do the trick. If it somehow doesn’t work, [peterquinn] has mused that a drastic upgrade to the vacuum may be necessary.

Tachometer Uses Light, Arduinos

February 24, 2018 by Bryan Cockfield 19 Comments

To measure how fast something spins, most of us will reach for a tachometer without thinking much about how it works. Tachometers are often found in cars to measure engine RPM, but handheld units can be used for measuring the speed of rotation for other things as well. While some have mechanical shafts that must make physical contact with whatever you’re trying to measure, [electronoobs] has created a contactless tachometer that uses infrared light to take RPM measurements instead.

The tool uses an infrared emitter/detector pair along with an op amp to sense revolution speed. The signal from the IR detector is passed through an op amp in order to improve the quality of the signal and then that is fed into an Arduino. The device also features an OLED screen and a fine-tuning potentiometer all within its own self-contained, 3D-printed case and is powered by a 9 V battery, and can measure up to 10,000 RPM.

The only downside to this design is that a piece of white tape needs to be applied to the subject in order to get the IR detector to work properly, but this is an acceptable tradeoff for not having to make physical contact with a high-speed rotating shaft. All of the schematics and G code are available on the project site too if you want to build your own, and if you’re curious as to what other tools Arduinos have been used in be sure to check out the Arduino-based precision jig.

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Harvesting Energy From The Earth With Quantum Tunneling

February 14, 2018 by Bryan Cockfield 117 Comments

More energy hits the earth in sunlight every day than humanity could use in about 16,000 years or so, but that hasn’t stopped us from trying to tap into other sources of energy too. One source that shows promise is geothermal, but these methods have been hindered by large startup costs and other engineering challenges. A new way to tap into this energy source has been found however, which relies on capturing the infrared radiation that the Earth continuously gives off rather than digging large holes and using heat exchangers.

This energy is the thermal radiation that virtually everything gives off in some form or another. The challenge in harvesting this energy is that since the energy is in the infrared range, exceptionally tiny antennas are needed which will resonate at that frequency. It isn’t just fancy antennas, either; a new type of diode had to be manufactured which uses quantum tunneling to convert the energy into DC electricity.

While the scientists involved in this new concept point out that this is just a prototype at this point, it shows promise and could be a game-changer since it would allow clean energy to be harvested whenever needed, and wouldn’t rely on the prevailing weather. While many clean-energy-promising projects often seem like pipe dreams, we can’t say it’s the most unlikely candidate for future widespread adoption we’ve ever seen.

Your Audio Will Be Back, Right After This Commercial Break

February 13, 2018 by James Hobson 37 Comments

[LittleTern] — annoyed by repetitive advertisements — wanted the ability to mute their Satellite Box for the duration of every commercial break. Attempts to crack their Satellite Box’s IR protocol went nowhere, so they thought — why not simply mute the TV?

Briefly toying with the idea of a separate remote for the function, [LittleTern] discarded that option as quickly as one tends to lose an additional remote. Instead, they’re using the spare RGYB buttons on their Sony Bravia remote — cutting down on total remotes while still controlling the IR muting system. Each of the four coloured buttons normally don’t do much, so they’re set do different mute length timers — customized for the channel or time of day. The system that sends the code to the TV is an Arduino Pro Mini controlling an IR LED and receiver, with a status LED set to glow according to which button was pressed.

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Play A Few Games Of Smash Brothers On The Go With A Portable Wii

January 27, 2018 by James Hobson 10 Comments

How would you approach a build that required you to hack apart a perfectly good console motherboard? With aplomb and a strong finish. [jefflongo] from [BitBuilt.net] — a forum dedicated to making consoles portable — has finished just such a task, unveiling his version of a portable Wii to the world.

While this bears the general appearance of a portable GameCube, it’s what inside that counts. A heavily modified Wii motherboard — to reduce size — forms this portable’s backbone, and it includes two infrared LEDs on its faceplate for Wii Remotes. A single player can use the built-in controller, but [jefflongo] has included four GameCube controller ports for maximum multiplayer mayhem. Although he’ll likely plan on taking advantage of the built-in AV Out port to play on a TV and charge port for those extended gaming sessions, four 3400mAh batteries — with an estimated four hour battery life — should keep him satisfied on the go until he can recharge.

While the electronics display an impressive amount of work, but the final piece is a sight to behold. Check out the demo video after the break!

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Cryptanalyse Your Air Con

December 17, 2017 by Lewin Day 19 Comments

Infrared remote controls are simple and ubiquitous. Emulating them with the aid of a microcontroller is a common project that hackers use to control equipment as diverse as televisions, cable boxes, and home stereos. Some air conditioners can be a little more complicated, however, but [Ken]’s here to help.

The root of the problem is that the air conditioner remote was using a non-obvious checksum to verify if commands received were valid. To determine the function generating the checksum, [Ken] decided to bust out the tools of differential cryptanalysis. This involves carefully varying the input to a cryptographic function and comparing it to the differences in the output.

With 35 signals collected from the remote, a program was written to find input data that varied by just one bit. The checksum outputs were then compared to eventually put together the checksum function.

[Ken] notes that the function may not be 100% accurate, as they’re only using a limited sample of data in which not all the bytes change significantly. However, it shows that a methodical approach is valuable when approaching such projects.

Thirsty for more checksum-busting action? Check out this hacked weather station.

Mike Ossmann And Dominic Spill: IR, Pirates!

November 29, 2017 by Elliot Williams 6 Comments

Mike Ossmann and Dominic Spill have been at the forefront of the recent wave of software-defined radio (SDR) hacking. Mike is the hardware guy, and his radio designs helped bring Bluetooth and ISM-band to the masses. Dominic is the software guy who makes sure that all this gear is actually usable. The HackRF SDR is still one of the best cheap choices if you need an SDR that can transmit and receive.

So what are these two doing on stage giving a talk about IR communication? Can you really turn traffic lights green by blinking lights? And can you spoof a TV remote with a cardboard cutout, a bicycle wheel, and a sparkler? What does IR have to do with pirates, and why are these two dressed up as buccaneers? Watch our video interview and find out, or watch the full talk for all of the juicy details.

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