Category Archives: Hack

Free Lojack for laptops (stolen laptop tracking service)

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***Edit 02/20/2012 – The information below is outdated and a new free opensource software is available – Check out www.preyproject.com for more information ***

My friends laptop was recently stolen when someone broke into her bedroom window which was left ajar during the day. Besides her sense of security, among the several items they stole was her laptop. Today, as we were chatting about her being able to borrow one of my old p3 laptops sitting around collecting dust, it dawned on me that a “lojack” type of software must be available for laptop and mobile computers, much like there is a “lojack” tracking service for automobiles. I did some google searching and came across several options…most of them paid. Such options available include products by Computrace (www.lojackforlaptops.com) and Tometa Software (www.tometasoftware.com). However, being as cheap as I am, I did not think shelling out $20-$40 on a subscription was a good deal if I could do this by using a free but less elegant method.

After a bit more googling, I stumbled upon a piece of software supplied by the University of Washington which was written under the GNU GPL, this basically means that it is free to distribute and modify. Its called Adeona (http://adeona.cs.washington.edu/) and is available for the Mac OS X (10.4 or 10.5), Windows XP/Vista, and Linux. A small unobtrusive program, Adeona runs as a service and periodically and randomly contacts an OpenDHT server to store the IP address and other associated information of the laptop when it is connected to the internet. This information can then be used to track down your computer, and in theory be recovered. Spiffy eh?

All would be swell, except for one (albeit huge) bug in its implementation. The software is in an early stage of development, and as it is now coded, has an issue connecting to and communicating with the OpenDHT servers (this is due to be fixed in the next release). In my quick evaluation, the included recovery tool was not able to grab the necessary information and did not return the useful results necessary to track a stolen laptop. Adeona in theory is one awesome tool, but its implementation has yet to deliver. Overall though, I feel this free and tiny alternative to the paid and more full featured software (although much more comprehensive in comparison), is just what is needed in todays era of mobile computing.

Ill be waiting till Adeona is fixed, and once that is done, will have it installed on all my mobile devices within the blink of an eye.

How to replace your address number light with a solar powered LED system

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A while ago, I picked up a solar panel from a Volkswagon dealership when my friend purchased a Volkswagon Jetta. On the way out of the dealership, I peered into one of their closets, and saw a bunch of these panels just sitting in boxes and piled on a shelf. The salesman told me they shipped with the new cars for use during transportation so the batteries would not drain out. They hooked up to the OBD sensor port and mounted on the windshield with suction cups and directly charged the battery from there. Pretty cool, and so was the salesman as he gave me and my friend one panel each.
The panel had been sitting around collecting dust till I scored some replacement UPS batteries (smaller 12v sealed lead acid batteries). But the only thing I could think of doing was cutting off the OBD sensor plug from the panel, and wiring it directly to the battery in order to give it a recharge. It was only until I noticed that our address number sign was missing a bulb and was wired to a small transformer above our water heater, did I begin to dream about a better life for the poor, lonely, solar panel.
Solar panel from nice VW dealership

Solar panel from nice VW dealership

I work at a computer liquidation company, so finding LEDs was no problem as many computer peripherals, server cases, and the like have these things mounted in/on them. I found three bright white LEDs (I figure they pull about 3.4volts drawing 20 milliamps each after googling), and found an appropriate resistor for use with the system (I used the LED resistance calculator at http://ledcalc.com/), by taking it from an old cisco router powersupply (its actually a 240 ohm resistor and the calculator called for a 100 ohm one, but it doesnt seem to affect it much).  I also upgraded my battery to use my old car battery that died from my car…I just charged it for several days with my solar panel till it was 12.7v.

diagram

The LED diagram that the LED resistance calculator gave me

As illustrated in the diagram, I wired my LEDs in series, attached the resistor to the positive lead on the LED chain and tested it with my battery. It worked!

Wired up LEDs in series and soldered the resistor to the positive lead

Wired up LEDs in series and soldered the resistor to the positive lead

I then unmounted my address number sign and had to pop out the female plug which the bulb would screw into. That gave me a nice sized hole to thread the LED string through.

LED string threaded and secured with some tape and a pluggy thing big enough to cram in the hole where the original plug used to be

LED string threaded and secured with some tape and a pluggy thing big enough to cram in the hole where the original plug used to be. In this picture, im using one of the UPS batteries to test it with. Now, I needed to unhook the original wiring which went from the address number sign to the transformer and reroute that with some wire to my car battery/solar panel setup. I went into the garage, and unscrewed the two wires from the transformer.

Transformer with the two wires still connected

Transformer with the two wires still connected

I then ran some speaker wire that I had laying around to those two wires to act as an extention, and connected it to my car battery.

Car Battery. You can see the gold speaker wire (connected to existing address sign wiring), and the black wires (connected to solar panel).

Car Battery. You can see the gold speaker wire (connected to existing address sign wiring), and the black wires (connected to solar panel).

I then reconnected the wires from the original address number sign out in the front of my house to the string of LEDs I tested earlier. I remounted (two screws) the address number sign, and replaced the hood which fit over the LEDs.
Address number sign remounted with hood.

Address number sign remounted with hood.

I was pleased that it was still working, and waited till dark. I did have to adjust the direction of the LEDs, as they were extremely bright and would streak a beam of light over only certain parts of the sign making it difficult to read. I ended up taking off the hood, lining the inside with tin foil, and oriented the LEDs towards the center of the sign and pointing towards the hood. The tin foil reflected and diffused the light so it was more evenly dispersed.

Address sign at night time.

Address sign at night time.

Im happy with the results, and the idea that I wont be spending any electricity on powering up a stupid address sign at night. It also makes my house easier to spot as the light from the LED is sort of bluish white, and looks completely different from the other houses in my neighborhood.