Seeing Through Walls Using WiFi

August 11, 2012 by Mike Szczys 20 Comments

Turns out you don’t need to be Superman to see through walls. Researchers at University College London have developed a way to passively use WiFi as a radar system. Unlike active radar systems (which themselves send out radio waves and listen for them to echo back), passive radar systems cannot be detected.

The system is small enough to fit in a briefcase, and has been tested through a one-foot-thick brick wall. It can detect position, speed, and direction of a person moving on the other side of that wall, but cannot detect stationary object. [Karl Woodbridge] and [Kevin Chetty], the engineers behind the prototype, think it can be refined to pick up motion as minuscule as a person’s rib cage moving with each breath. For some reason we get the picture in our mind of that body scanner from the original Total Recall.

[via Reddit]

[Image Credit]

Blinking Light Switch

August 11, 2012 by Mike Szczys 15 Comments

In addition to being a great replacement for that aging eye patch, these specs act as a light switch. By watching your eyelids, they are able to kill the lights whenever you blink.

The installation is a shared experience piece conceived by [Michal Kohút]. He wanted to illustrate the constant blinking we all do but rarely think about. The system uses an Arduino to capture events from the blink sensors and switch the lights accordingly. This way the wearer doesn’t experience a loss of illumination, but the observer does. Check out the video after the break for a quick demonstration.

One of the commenters from the source article shared a video link to another blink-based light project. That one uses electrodes attached to skin around your eye in order to detect eyelid motion.

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Building A Coal Forge

August 11, 2012 by Mike Szczys 21 Comments

We don’t get to see Blacksmith hacks around here too often. But even if they were rolling in on a weekly basis we think this one would be considered the special expanded edition with full-color centerfold. The sixty-five images in this coal forge build log are all commented and just begging to steal your attention for part of the afternoon.

The build mostly involves fabricating a system for injecting air into the forge and providing a mechanism for evacuating the waste ash. [BillDaCat] starts with a 3″ pipe as the ash dump, adding a latching door used to empty it when full. He then welds together a metal trough with a slotted bottom to hold the fiery fury, attaching the ash dump below. He uses a plasma cutter to add an opening in the upper portion of the ash dump for a blast gate.

If you’re excited about his build you should also check out the metal pour and the induction furnace.

[via Reddit]

How Not To Dim EL Panels, TRIACs!

August 10, 2012 by Jesse Congdon 15 Comments

We’ve all been there: an exciting brilliant idea, scratched onto a napkin, hastily plugged into a breadboard, all for naught. Even the best ideas sometimes suffer from a heavy dose of reality. [Ch00f] over at ch00ftech recently had a similar experience dimming an EL panel of his using a TRIAC and some clever waveform manipulation. Instead of tossing the parts ~~across the room in a fit~~ aside and moving on he goes into a detailed analysis of what went wrong.

This method differs from the way most EL drivers dim output loads, instead of chopping the output like a PWM controlled LED the TRIAC snips the ends of the waveform and makes an ugly but less powerful output. The issue with this method is that when you cut the waveform during non-zero crossings it causes massive current spikes. These can wreak havoc on a cheap EL inverter and generally cause headaches all around. [Ch00f ] speculates that his woes may be due to the fact that EL wire is a capacitive load, causing voltage to fall out of phase with the current. This is one of those engineering problems with a thousand and one answers, we can’t wait to see what he comes up with.

Check out the writeup for all the “deets” (as [ch00f] would say) as it is a pretty good primer on TRIAC operation. If there isn’t enough glowy wire in this post you can also check out this sound reactive panel or an informative guide on EL or even more from [ch00f] in general.

Swapping Out Eee PC BGA Chip For 1.6 GHz Upgrade

August 10, 2012 by Mike Szczys 37 Comments

Personally we find this Ball-Grid Array chip-swap rather horrifying. But if you want to beef up the processor on your 701 Eee PC this is what you’ll need to go through. Not only did [Red Fathom] upgrade to a 1.6 GHz chip, but he managed to get the computer to boot up with the new hardware in place.

BGAs are notoriously hard to solder. This hack pulls it off using just a hot air gun. [Red Fathom] heats the board from the underside until the solder melts and he can pluck off the old chip. He then uses a solder braid and iron to remove extra solder from the footprint. After a little cleanup with a cotton swab and some flux he plops in an Intel Pentium M LV 778. It doesn’t look like he added any solder after the cleaning process. Perhaps he’s relying on the small amount left on the tinned pads of the board?

After the break you can see the soldering process and a video of the new processor booting Xandros.

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NAS-based Transcoding Facilitates Security Cam Viewing On IPhone

August 10, 2012 by Mike Szczys 14 Comments

[Zitt] has a security camera which will send him messages any time it detects motion. However annoying this might seem, we’re sure he has his reasons for needing this much immediate feedback. The real problem comes when he goes to view the feed on his iPhone. His solution is to turn the camera’s notifications off, and use his own script to transcode a clip and shoot off an email.

As you can see above, the end result is a concise email that includes the recently captured clip, as well as links to the live feed. He has been storing the clips on an LG N4B2 Network Storage Server (NAS) and since he’s got root access to the Linux system on the device it was an easy starting point for the new system. After he compiled FFmpeg from source (which handles the transcoding) he started work on the script which backs up the recordings and sends the email messages.

One thing he wants to add is a method to clear out the old backup videos. Having encountered a similar issue ourselves we decided to share our one-liner which solves the problem. Find it after the break.

Continue reading “NAS-based Transcoding Facilitates Security Cam Viewing On IPhone” →