You probably saw [Phillip Torrone] and [Limor Fried]’s twittering Kill A Watt earlier this week. It was an entry in the Core77/Greener Gadgets Design Competition. We saw a little bit about how it was assembled, but now they’ve posted a full guide to assembling the hardware. Each Kill A Watt gets an XBee radio that transmits back to a receiver that logs the power usage. The difficult part when putting this design together was the XBee required 50mA when transmitting. This is well above the Kill A Watt’s internal power supply. They remedied this by adding a 10,000uF supercap to act as a rechargeable battery. The daily twittering is just a side-effect of the project. The Kill A Watts transmit every 2 seconds, so you’ll get a very accurate report of your power usage. This is a great project for renters who can’t permanently modify their power infrastructure. Each Kill A Watt can support quite a few appliances since they’re rated for 15A, ~1800W.
Here’s an odd little footnote we found while perusing the Comic Tools blog. [Matt Bernier]’s blog is dedicated to drawing and inking tutorials for comic artists. He uses a lot of example photographs that involve both hands. This week, at the bottom of his post on cleaning brushes, he included a photo to illustrate how he takes all of these point of view shots. The camera is strapped securely to his head using an old lanyard. He can see the display and access the controls on the back. After composing his shot, he just sets the timer, and you get a picture of what the process looks like from his perspective. Sure, it looks silly from this angle, but it really helps out the posts.
As a followup to last week’s post on automated protocol analysis, [Tod Beardsley] has written up how to start analyzing a protocol manually. He walks through several examples to show how to pull out the interesting bits in binary protocols. His first step was sending 10 identical select statements and capturing the outbound packets. He used the Ruby library PacketFu to help with the identification. It compared the ten packets and highlighted one byte that was incrementing by four with each packet, probably a counter. Looking at the response indicated a few other bytes that were also incrementing at the same rate, but at different values. Running the same query on two different days turned up what could be a timestamp. Using two different queries helped identify which byte was responsible for the statement length. While you may not find yourself buried in HEX on a daily basis, the post provides good coverage of how to think critically about it.
We’ve all seen these on the side of the road and wondered how we could change the message. It turns out that it is actually pretty easy. There’s a keypad inside for programming that is often still set with a default password of “DOTS”. Even if the password has been changed, you can reset it right there pretty quickly. We shouldn’t even need to warn you that it is illegal to tamper with these, so unless there really are zombies ahead, you probably shouldn’t mess with it.
A leyden jar is basically just a simple home made capacitor. We’ve shown you how to make them before. This, however, is how you make a ridiculously large one. [Nickademuss] used a five gallon bucket to make his leyden jar. That’s five whole gallons of lightning. The video, which you can see after the break, shows it light up the entire room when it lets out a fairly formidable spark. This is dangerous folks, be careful.
Continue reading “Leyden jar of DOOM.”