Frankenstein’s lawnmower

[phantompinecone] has an electric mower that worked great for about 4 seasons, and then the battery started to die. A replacement was installed but it started being a pain after the first season. Since the battery was brand new (and probably costly too) there must be something else.

Checking the brushes, which were fine, the next logical place was the switch.These mowers are just a battery, motor, and switch. Yanking it apart there was indeed a problem, they were chewed up and corroded, not allowing full electrical contact. So [phantompinecone] replaced the simple mechanical switch with a MOSFET.

Electrically there is an IRF1405 MOSFET, some resistors to pull signals around and a couple diodes to A) keep the back emf from the motor in check, and B) drop the voltage going into the fet from 24volts to 12. Problem solved, and the motor should not have anymore trouble caused by a junked up switch.

The concepts behind robotic maze solving

[Patrick McCabe's] latest offering is a well-built maze-solving bot. This take on the competitive past-time is a little more approachable for your common mortal than the micro-bot speed maze solving we’ve seen. Don’t miss seeing the methodical process play out in the clips below the fold.

The playing field that [Patrick's] robot is navigating is made up of a electrical-tape track on a white background. The two-inch tall double-decker bot is every economical. It uses an RBBB Arduino board to read an optical reflectance sensor array made by Pololu, then it drives a couple of geared motors using an L293D h-bridge breakout board. But we already know that [Patrick's] a talented robot builder, this time around we’re happy to see his in-depth discussion of how to program a robot to solve a maze. In it he covers all of the different situations your robot might face and how to deal with them. Once you’ve dug through all of the concepts, dust off that bot you’ve got lying in the corner and start writing some new firmware.

[Read more...]

BlinkM smart garage door opener


Calling Canada home, Hackaday reader [TheRafMan] has seen his share of bitterly cold winters. He also knows all too well how hard it is to get his cars started in the morning if somebody happens to leave the garage open. After the door was left open overnight for the second time this last winter, he decided that it was time to add an indicator inside the house that would alert him when the garage had not been closed .

Inspired by our BlinkM Arduino coverage a short while back, his circuit incorporates a BlinkM as well as several other components he already had on hand. He disassembled the garage door switch situated in the house and fit the BlinkM into the switch box once he had finished programming it. A set of wires was run to the BlinkM, connecting it to both a power supply located in the garage as well as the magnetic switch he mounted on the door.

The end result is a simple and elegant indicator that leaves plenty of room for expansion. In the near future, he plans on adding an additional indicator strobe to let him know when the mail has arrived, not unlike this system we covered a few months ago.

Stick around to see a quick video demonstration of his garage door indicator in action.

[Read more...]

IDE bus sniffing and hard drive password recovery


shackspace member [@dop3j0e] found himself in a real bind when trying to recover some data after his ThinkPad’s fingerprint scanner died. You see, he stored his hard drive password in the scanner, and over time completely forgot what it was. Once the scanner stopped working, he had no way to get at his data.

He brainstormed, trying to figure out the best way to recover his data. He considered reverse engineering the BIOS, which was an interesting exercise, but it did not yield any password data. He also thought about swapping the hard drive’s logic board with that of a similar drive, but it turns out that the password is stored on the platters, not the PCB.

With his options quickly running out, he turned to a piece of open-source hardware we’ve covered here in the past, the OpenBench Logic Sniffer. The IDE bus contains 16 data pins, and lucky for [@dop3j0e] the OpenBench has 16 5v pins as well – a perfect match. He wired the sniffer up to the laptop and booted the computer, watching SUMP for the unlock command to be issued. Sure enough he captured the password with ease, after which he unlocked and permanently removed it using hdparm.

Be sure to check out [@dop3j0e's] presentation on the subject if you are interested in learning more about how the recovery was done.

Hacker Typer lets you turn jibberish into useless code

We generated the screen full of code seen above literally by bashing a hand on the keyboard repeatedly like a monkey. You know, just like how hackers are portrayed in the movies? Hacker Typer makes you look like you know what you’re doing even though you’re too lazy to do something real. It’s a pointless website that’s none-the-less worth a few moments of your time just for the sake of amusement. You’ll be greeted with a set of options. The first lets you decide what pre-determined text will appear as you type. The rest are for page title, foreground and background colors, and number of characters that will appear with each keystroke.

The default features start off with three characters generated for each keystroke, another annoying staple of Hollywood film making. Oh well, even movies that try really hard to get things right end up getting under the skin of someone. Case in point, the Linux shell readout from Tron Legacy.

[via The Presurfer]

Hack a Day Links: April 27, 2011

Remaking the first video game

At the Revision 2011 demo compo, a museum project called [MEGA] won first place in the “Wild” category with their zero bit recreation of “tennis for 2”. Entirely made of analog electronics, the retro game completes its presentation on a round o-scope screen. You can see a video of it after the break.

Mint-tin bicycle computer

[Alexdlp's] newest instructable is a attractive and compact bicycle computer running off of an Arduino, and sports the usual bike features. It does not stop there, adding in a 16×2 LCD gives more room for data in both numeric form and bar graph form, and adding in a pair of radio modems allows that data to be fed back home where it can be logged and compared, perfect for the more serious biker.

8085 Reference Card

If you enjoy retro computers, or would like to make your own, you will find this Intel 8085 reference card is a real treat. Based on a original reference card, it has been expanded to give more detail for additional interrupts, electrical reference, T-State timing, and undocumented instructions.

Connect a SNES controller to your Android phone

[Bruno] wanted to be able to use a real SNES controller with the emulator on his HTC Android phone, packing in an Arduino, 6 AA batteries, and a breadboard and mission accomplished! Hardly as portable as the phone, but we commend the “get it done” sprit. Join us after the break for a quick video.

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WonderHowTo inteview of [Matthias Wandel]

If you’re an avid Hackaday reader chances are that you immediately recognized [Matthias Wandel's] name. He’s been featured many many times to go along with his many many talents. Most notably, his ability to do some amazing things with wood. But really, it’s the idea that counts, and he seems to have a duffle bag full of them. [Rachel adn Justin] over at WonderHowTo recently published a full interview with Mattias. In it he shares his thoughts on where some of these ideas come from, how he approaches his projects, and even shares some advice for those just getting started.

This is usually the time where we make a witty remark and try to work in links to feature articles from the past. If we were limited to just one it would be pretty tough (although there’s a special place in our hearts for the wasp sucker). Luckily we’re not limited, so here’s a list of some of [Matthias'] projects which Hackaday covered previously: