Hack a Day favorite [Mikey Sklar] is back with a new project. Mini-D is a battery desulfator. If a 12V lead-acid battery sits with a voltage below 12.3V, sulfur crystals will begin to form on the lead plates. This crystal growth increases the internal resistance and eventually makes the battery unusable. A battery desulfator sends high frequency pulses through the battery to create a resonance that will break up the crystals. On a 60lb automotive battery, it will take approximately three weeks to completely desulfate. You can find schematics plus a dozen lines of code for the ATmega169 on his site. Embedded below is a video where he explains the device and other techniques like load testing.
It seems one of our commenters took great umbrage with [PodeCoet] not documenting his capacitive discharge cutting properly. [PodeCoet] had been waiting till he got the full spot welder working before publishing, but he’s expedited the work after all our whining. Check out his full writeup of the device in its current state. It uses a 1Farad audio cap for storage. A dsPIC monitors all of the voltage sources and regulates charging. A nice touch is the tactile switch on the electrode.
Reader [john] finished up his home power monitor over the holiday weekend. It uses a pair of current transducers clamped onto the mains. These output 0-3V and are read by the Arduino’s ADC. The Arduino averages samples over a 20 second period, calculates power used, and uploads it using an Ethernet Shield. The shield can’t do DNS lookups, so he uses a WRT54G to negotiate with the remote webserver. He admits that the system could be more accurate; it can’t detect small loads like wall warts. He also says that money could be saved by talking serial to the router instead of over ethernet. Here are the current usage charts.
You can find many power monitor projects like this in out Home Hacks category.
The TV-B-Gone has proven to be a dangerous and versatile gadget. At Interactive Matter, they created an even smaller version with more sneaking potential. Called the µTVBG, it packs an entire TV-B-Gone in a 1.4 x 2.5 cm footprint and even has room for a programming header. He found some high-powered surface-mount IR LEDs that would match the original TV-B-Gone’s power. To drive the board, they used a CR1220 button battery on the bottom of the board. The whole thing is smaller than your thumb and should be easier to hide next time you wreak havoc.
Capacitive discharge cutting provides more control than linear transformer versions. A very large capacitor is charged to a precise voltage and then discharged through the material to produce a controlled cut. The same device can also be used for spot and tab welding. A video of copper roof flashing being cut is embedded below. An example of a linear transformer can be found in our our How-to: build your own spot welder.
This antenna tuner is controlled remotely using geared motors and legos. The tuner needed to be closer to the antenna for performance reasons. This created a problem; most of the radio gear is inside while the tuner is outside. The gear motors and Legos combine to form a closed loop servo, operating two air core caps and an inductor switch. A control box placed near the radio is hard wired to the modded tuner outside. We would like to see something like this under gesture control using the Wii MotionPlus + Arduino.
posted Jul 3rd 2009 11:13am by Ian Lesnet
filed under: news
Update, Saturday July 4th, 2009: All preorders are closed.
Today is the last day to pre-order a Bus Pirate. Get your own Bus Pirate, fully assembled and shipped worldwide, for only $30. We don’t plan to make more soon, this could be your last chance.
A special shout out to our partner, Seeed Studio, who handled the rush of orders like pros. The first pre-order is already being manufactured, and will ship as soon as possible. Seeed still has a few V2a PCBs if you’d like to roll your own Bus Pirate.
You’ve made this pre-order a huge success, and we’d like to make more projects available in the future. Were you just interested in the Bus Pirate? Should we arrange pre-orders of future Hack a Day hardware? Are there any past projects that we should revisit?
Here’s an interesting concept, the bot pictured above has no internal control mechanisms. His claims to have built the smallest bot are dubious, considering it requires a much larger control platform to function, so lets just set that aside and look at how it works. The bot itself is basically a hollow box with a hinged manipulator mounted on it. He has then built a modified CNC type structure with various magnets below a platform. The magnets can move the bot and control the manipulator (assuming the bot isn’t trying to pick up anything magnetic). He talks about this being a possible control scheme for smaller bots, though we think he would have to make some major advancements to his magnetic controls for accuracy’s sake. As for his claims of being the smallest, well, we’re sure we’ve seem similarly sized bots, even hexapods, that were completely self contained.
Here’s something every office probably needs. Ours does at least. It’s a WTF counter. When the office gets just a little too weird, someone hits the button and it gets logged. It’s probably pretty easy to judge the day by the WTF chart. The button is connected to an Arduino that updates the status on a local web server. We can imagine a nice bar graph of WTFs per day, or possibly a pie chart with normal time vs WTF time. Unfortunately, imagining is all we’re going to do. They didn’t include any examples of the visualizations. Can you imagine saying something to a co worker just for them to promptly march over and slap the WTF button? Maybe we don’t need one.
SparkFun has started to release some of their kits as open-source hardware. Projects such as ClockIt, a simple alarm clock, have their schematics, board designs, and source code released under the CC-by-sa license. Although most of their widgets and projects already had example code and schematics available, they are now using an open-source license. They are joining adafruit and EMSL and others in pushing OSH, but it is interesting to see an established company turn to this. Normally, startups do this to encourage early adoption.
[Jen Hui Liao] created a device that guides the user into drawing a portrait of themselves. Dubbed Self-Portrait Machine, it comments on how much in society is created by machines and we are dependent on them. Unlike previous drawing robots, the user is part of the sketching process. The machine holds the users hands and uses stepper motors and servos to move them around like a LOGO turtle. Liao promises to have more details available soon. Video of the machine after the jump.
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.
Scratchbot is designed as a rescue bot, going places where there is low visibility. It’s defining feature is the fact that it uses “whiskers” to feel for things. We feel like this is a little gimmicky. If it is a low visibility situation, wouldn’t IR or audio, possibly sonar be a more effective? How would it differentiate between different physical obstacles? Are the whiskers really new? Aren’t they really just bump sensors? Maybe they have something a little more complicated going on. There was another recent bot that utilized whiskers and compared different tactile profiles to determine what it was touching.
Update, Saturday July 4th, 2009: All preorders are closed.
A probe cable makes it easy to connect the Bus Pirate to a circuit and get hacking. Good test clips make quick connections on cramped PCBs without causing short circuits. We made two cables for the Bus Pirate v2, keep reading for an overview of our designs and list of part suppliers.
Friday, July 3, 2009 is the last day to pre-order a Bus Pirate. There’s only two days left to get your own Bus Pirate, fully assembled and shipped worldwide, for only $30.
