Bathroom fan that switches itself on when it gets steamy or smelly
At first we thought that [Brandon Dunson] was writing in to tell us he’s too lazy to fix his bathroom fan. What he really meant is that simply replacing the unit isn’t nearly enough fun. Instead, he developed his own bathroom fan trigger based on stinky or humid air conditions. He didn’t publish a post about the project but we’ve got his entire gallery of build images after the break.
The initial inspiration for the project came from a twitter-connected fart sensing office chair. Hiding behind the character display you can see the MQ-4 methane gas sensor which he picked up for the project. But since there’s also a shower in the bathroom he included a humidity sensor with the project. Both are monitored by an ATmega328 which averages 10 readings from each sensor before comparing the data with a set threshold. If the sensors read above this level a relay turns on the bathroom fan.
Don’t be confused by the small DC fans seen above; [Brandon] is still using a proper exhaust fan. These are just used to help circulate the air around the sensors so that low-hanging smells will still trigger the system. This has got to be the perfect thing for a heavily used restroom.
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Raspberry Pi reaches critical mass as XBMC hardware
For years I’ve been dreaming of a streaming media device that could just be stuck to the back of a television. Since XBMC has been far and away my favorite set-top box software, I’ve closely monitored hardware developments that can run that package. Now I think it’s time to declare that the Raspberry Pi has achieved the base specifications to be branded the XBMC device that rules them all.
There are a huge range of opinions on this topic, but please hear me out after the break to see what has brought me to this conclusion.
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MSP430 Launchpad Game of Life shield
[100uf] built an LED matrix shield for the MSP430 launchpad. His goal with this design was to have it play Conway’s Game of Life. It does just that, as you can see in the clip after the break. But it’s just waiting to learn some more tricks. After he tires of watching the cellular automaton he can try his hand at making some LED pendant animations.
As you can tell, the board was made in his home workshop. It’s not etched, but milled using the CNC machine shown in this image gallery. This is a single-sided PCB, which works well enough for the surface mount components and the downward facing pin sockets. But we wonder how difficult it was to solder the legs of that 8×8 LED matrix. It does have plastic feet at each corner that serve as standoffs to separate the body from the copper layer. But it still looks like a tight space into which he needed to get his iron and some solder.
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How to build OpenOCD with Stellaris Launchpad support
The stable version of OpenOCD doesn’t have support for the ICDI protocol used by the Stellaris Launchpad board. But it is pretty easy to build your own OpenOCD from source after patching it to use the protocol.
We’ve already seen an open source tool used to flash binary images to the TI ARM board. But that can’t be used with GDB. With the recent inclusion of USB-based ICDI in the OpenOCD development branches we gain all the features that come with the package. We’re quite happy hear about this as we use OpenOCD for many hardware architectures and this makes development for this board feel more like normal.
Our Stellaris Launchpad hasn’t just been sitting in the closet since we got it. We’ve learned a lot by using the lm4tools to program the chip as we work our way through the online workshop. We’re really beginning to like the Stellarisware peripheral library that has been provided. For us it works in a much more intuitive way than the one that STM uses with their ARM Discovery boards. We’d recommend taking a look at the workbook PDF (which is basically a verbose listing of what’s in the video series) and the library reference (called SW-DRL-UG-9453.pdf) which is in the docs folder of the Stellarisware package.
[via Dangerous Protoypes]
Large area x-ray detector
This is an x-ray detector built by [Ben Krasnow]. It’s an interesting combination of parts working with an oscilloscope. The result is an audible clicking much the same as you would hear from a Geiger counter
He’s measuring backscatter, which is the reflection of x-rays on other objects. Because the signal will be quite weak compared to waves emitted directly from an x-ray source he needed a large collector to measure them. He started by gutting an x-ray image intensifying cassette. This has a phosphor layer that glows when excited by x-rays. The idea is that the glowing phosphors do a better job of exposing film than direct x-rays can. But [Ben's] not using film. He built that pyramid-shaped collector with the phosphor material as the base. At the apex of the pyramid he mounted a photomultiplier tube (repurposed from his scanning electron microscope) which can detect the excited points on its surface. His oscilloscope monitors the PMT, then issues a voltage spike on the calibration connector which is being fed to an audio amplifier. Don’t miss his presentation embedded after the break.
[Ben] mentions that this build is in preparation for a future project. We’d love to hear what you think he’s working on. Leave your guess in the comments section.
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Python script lets you monitor multiple serial devices at once
Not knowing what’s going on inside of your electronics projects can make it quite difficult to get the bugs out. [John] was bumping up against this problem when working on wireless communications between several devices. At just about the same time his friend came up with a script with lets you monitor multiple serial devices in one terminal window.
We’re used to using minicom, a Linux package that does the job when working with serial connections of all kinds. But [John] is right, we’re pretty sure you can only connect to one device per minicom instance. But [Jim's] Python serial terminal (available in this git repository) allows you to specify multiple devices as command line arguments. You can even use wildcards to monitor every USB connection. The script then automatically chooses a different color for each device.
The image above is from [John's] wireless project. Even without any other background this shows how easy it is to debug this way rather than tab back and forth between windows which gets confusing very quickly.
POV wheels for a longboard