[vimeo=http://vimeo.com/5989780]
[Andrew Rapp] sent in this project called Droplet. He’s been doing work with Xbees and Arduinos together and built this little toy. He describes it as “sort of like a Chumby”. It has built in services for Twitter, Google Calendar, News, Gmail, etc. You can download the full source code and plans on his site. His next planned revisions include possibly running it from a sheevaplug, making a nice case for it, and utilizing the unused pins of the arduino.
[WaveRider] is using a type of phase shift keying called BPSK to transmit digital sound and video for remote telemetry. Though a higher signal to noise ratio (SNR) is generally sought after with communications, legal limitations are imposed on total radiated power. To balance the two headed beast, he opted out on frequency shift keying due to binary shift keying’s ability to work with lower SNR. This adds the difficulty of properly reconstructing the digital signal at the receiver. A PLL based carrier regeneration circuit is used to reconstruct the signal. Using the Rabit2000 processor as the host controller on both transmitter and receiver, 96KB/Sec serial data is obtained. On the other side of the spectrum is the Homemade regenerative tube radio.
There are no microcontrollers in this project. In fact you wont find a single transistor. This classic regenerative tube radio, modeled after an early 20th century homebrew is complete with schematic and additional photos. For those who are not familiar with tube designs and for simplicity, the regeneration circuit can be thought of as feedback though this relation may be argued. Read the rest after the break which includes a crash course in tube operation. Continue reading “Homemade Regenerative Tube Radio”
Here is a classic project used to increase wireless signal strength. Cantennas focus using a waveguide very much like a magnifying glass focuses light. [Robert] made a Natural Light beer cantenna, pictured in the upper left. His approach used three beer cans, a paper towel holder, and a shower curtain rod. On the tipline, he noted a signal boost from 11Mbps to 54Mbps. This is certainly something we can hack together if our room lacks adequate signal. Read about parabolic and seeking versions after the break.
Lifehacker wrote a guide for cracking a WiFi network’s WEP password using BackTrack. BackTrack is a Linux live CD used for security testing and comes with the tools needed to break WEP. Not just any wireless card will work for this; you need one that supports packet injection. The crack works by collecting legitimate packets then replaying them several times in order to generate data. They point out that this method can be hit-or-miss, especially if there are few other users on the network, as the crack requires authenticated packets. We covered cracking WEP before, but using BackTrack should smooth out compatibility issues.
[youtube=http://www.youtube.com/watch?v=Zrb58Pcuos0]
[Hunter, Kyle, and Dylan] sent us some information on their Barbie Web Rover. It’s an old barbie power wheels jeep that’s been converted to a web enabled remote control car. They ripped out the old drive train and tore out the steering system. The rear tires are now independently driven for steering. It’s using an Arduino to control the motors and an Acer Aspire loaded with linux for the higher functions. It’s cool that they mention the farthest test being over 1600 miles away, but when it’s web enabled, does distance really matter?
They mention that the coolness factor is proportionate to the size and we have to agree, as long as they keep it small enough to not cause any real damage. You can build a web enabled rover with a little more effort from just a router, if you don’t want to give up your laptop.
Reader, [Andres Leon], has two adorable cats with very specific dietary needs. Instead of altering his schedule, he donned his hacking hat and designed a very solid cat food dispenser. The dispenser consists of a rotating drum with a slot in it and a PVC pipe Y-fitting to distribute the food evenly. The brains of the machine is an Arduino Deumillanove and an XBee module. The unit can be controlled by a web interface or it can run completely standalone. [Andres] ran into a problem where the drum’s resistance to turning varied based on how much food was inside. He solved this with a clever laser position indicator. A piece of plywood is lined up with the slot at the top so that whenever the slot is facing up it keeps the laser from shining on a photoresistor. The cats were afraid of the servo noise at first, but now they run to their bowls whenever they hear it.
