TI's msp430s are crazily power-efficient. Worth a look if you want to run a long time on batteries. Or indeed fruit: <a href="http://www.youtube.com/watch?v=nPZISRQAQpw" rel="nofollow">http://www.youtube.com/watch?v=nPZISRQAQpw</a>
Ever since these small devices have been in production, I've always wondered about their potential use in clandestine installations. Obviously things like the Shiva Plug are almost capable of hiding in plain site, so long as there's a plug near by.<p>I've also wondered if there are clamp-on induction taps that can be clamped to power lines (say, above the tiles in a corporate bathroom powering the lights) and drive low-power devices like a small Arduino.<p>This 9V hack is really cool for sensors and the like, but it wouldn't power a full OS with wireless AP ability for very long.
This is a wonderful little piece of information. Thank you.<p>I had the crazy idea a while back about stuffing a micro-controller, temp+humidity sensor, piezo speaker into my guitar case to let me know if the Humidity got out-of-band but I couldn't see how to get this to run for more than a few days with out having a gian5t battery pack or having to plug it in to the wall.<p>Now I know, and knowing is half the battle.
Excellent writeup. Thanks. Are you planing on covering
the "What else can you do?" stuff in more detail in another
post? If not, then adding a few more details/links in that
part would be an idea for improving something that's already
great.
I have a dark corner near the entrance door and I made a battery-run light (2 LEDs - to light up the key hole) with very simple logic: when you press the button, it lights up for 2 minutes, then blinks for another 2 minutes; then blinks faster for another minute; then goes dark.<p>The button is wired to "reset" pin of an attiny45, the LEDs are connected to two pins of the chip, and the code, predictably, ends with a low-power sleep instruction.<p>Two 2100mAh AA-sized accumulators provide the power.<p>I "launched" it into use about 4 months ago (I forgot the exact date), still did not have to recharge.
I'd love to see a pre-packaged low power optimized Arduino. This would open up a ton of possibilities that I daydream about. I don't want to solder chips myself, though.
Sparkfun also has an exceptional write up on how to get into the microamp ballpark:
<a href="http://www.sparkfun.com/tutorials/309" rel="nofollow">http://www.sparkfun.com/tutorials/309</a><p>The article's try and see approach is very detailed and a great read for anyone looking to get into prototyping with AVR for battery based projects.
A good option when you only need to monitor a few signals is to use an xbee series 2 module, that will also wirelessly transfer the data to a central server. It can run attached to an Arduino, but also stand-alone. "Building Wireless Sensor Networks", by Robert Faludi, is a very readable introduction.
Very cool. This is how final projects should be -- we shouldn't just shove the entire prototyping board into whatever we're making.<p>Any clues for how to keep 9v batteries providing enough juice when they're in the fridge? I'm trying to build a fridge monitor: <a href="http://gilgamech.blogspot.com/2013/02/wireless-temp-sensor.html" rel="nofollow">http://gilgamech.blogspot.com/2013/02/wireless-temp-sensor.h...</a>