Don’t want dogs pooping on the front lawn? You could put up a sign, your could chase them away like a crotchety old miser, or you could build a motion detecting sprinkler system. It’s pretty hard to line up for a doody when you’re getting sprayed in the face (or worse) with cold water.

The setup is pretty simple. The bump-in image above shows the view from a webcam. The server monitoring the video is running software that detects motion between one frame and the next. When it sees something in the right position it signals an Arduino to trigger the solenoid which has been holding back the water. Check out the movie after the break which shows [Phil Tucker] tramping across the grass to trigger the  trap.

Sprinkler hacks are always a lot of fun. This variable-range sprinkler is still one of our favorites.

Like many hackers of late, [Rick] has been experimenting with connecting Arduinos to the Internet with a disused WiFi router and an installation of OpenWRT. Unlike his fellow makers, [Rick] thought it would be wasteful to dedicate a single router to one Arduino project, so he used a small, low power wireless module to connect up to 30 Arduinos to the Internet.

Just as in a few recent builds (1, 2), [Rick] found an old Fonera router sitting in a box at his local hackerspace. After installing OpenWRT, [Rick] connected a very small wireless module to the router’s GPIO pins and patched the firmware to put an SPI bus on the router.

Now, whenever [Rick] wants to connect an Arduino project to the Internet, all he needs is a $4 radio module. This radio module connects to the router, and the router handles the networking requirements of up to 30 DIY projects.

If you’re looking to build an Internet-enable sensor network, we honestly can’t think of a better or cheaper way of going about it. Nice job, [Rick].

I wrote earlier this week about an applied electronic circuits course for our bioengineering majors  and added some more project ideas in another post.  This weekend, while in southern California for my niece’s wedding, I was given another idea for a project by my sister: a pulse oximeter.

I knew that a pulse oximeter worked by looking at ratios of two different wavelengths of light shining through a finger or earlobe, which have different absorption by oxyhemoglobin and deoxyhemoglobin, but I had never thought about the details.  The first thing that concerned me was how a single ratio of two light intensities could be used—there must be huge variations in how much absorption there is that have nothing to do with oxygenation of hemoglobin.  Rather than puzzle through this on my own, I looked up the Wikipedia article on pulse oximetry.

It turns out that different techniques have been used over the decades.  Some of the early methods used more than two wavelengths of light including some that did not distinguish between the two states of the hemoglobin, in an attempt to quantify the total amount of hemoglobin as well as the ratio of oxy- to deoxy-.  The modern approach, though, is much simpler and more elegant.  The ratio measurements are made repeatedly, and only the fluctuating part of the readings is used.  The arterial blood flow shows a strong pulse signal (at around 0.5–3 Hz), while contaminating signals (hemoglobin in veins, absorption due to tissue other than hemoglobin, fingernail polish, …) are constant. By ignoring the DC signal and using only the fluctuating signal, the oxygen ratios are fairly easily measured.  Note that a pulse is essential to this measurement—continuous flow would not work—hence the name “pulse oximetry”.

There is at least one homebrew pulse oximeter on the web (like this one done by some Polish students and described in Polish, with a Google translation).  As far as I can tell, they used a PWM output from the microprocessor to provide signals alternately to the two LEDs, and to demultiplex the signals from the sensor and do separate analog filtering of the two signals.  It would probably make more sense to reduce the sampling rate to about 100Hz and do all the processing digitally. One thing they did that might be a bit trickier on the Arduino was to adjust the current to the LEDs to keep the DC signal level roughly constant, despite differences in the thickness and opacity of the fingers they were shining the light through.  The Arduino provides PWM outputs, but not real digital-to-analog channels.

They also do not seem to have thought about how to calibrate the device, which could be a problem for our lab also. Since commercial pulse oximeters only cost about $30 these days, we could simply have a couple in the lab for students to compare their results to, making a calibration chart of their reading vs the commercial reading.  (The hard part would be finding variation in oxygenation, since every one in the lab will likely be in the normal range of 95–99% oxygenated.)

The pulse oximeter would be a nice step up from the simple one-channel pulse sensor.  Unfortunately, most of  the design work seems to be on the digital side, rather than the analog side, which may make it a poor fit for the circuits course.

If you’re a MAKE regular, you know that we feature a lot of Arduino projects. It’s such a popular and easy to use microcontroller, I don’t think a day goes by without a blog post that mentions Arduino. But what if you’re totally unfamiliar with this popular physical computing platform? Where do you get started? To answer that question, we created this video. So if you have a friend or relative who has been asking “what’s an Arduino?” You can point them here. They’ll get an overview of what it is and what’s possible with it.

And if you’re here because you’re new to Arduino, there’s no better way to learn than fearlessly jumping right in getting started. For that, I recommend Maker Shed’s Getting Started with Arduino Kit, and not because I work for MAKE. A few years ago—before I worked here—I started playing around with an earlier version of this kit and it lead me to a huge breakthrough. As a kid, I tried a few times to teach myself electronics but never got very far. The Getting Started with Arduino Kit is what I wish I had as a kid. When I uploaded the blink sketch and saw that LED flashing, it was a moment of delight. Tinkering with electronics quickly became my hobby and then my livelihood. So if you’re on the fence about trying it out, I implore you to get off that fence and join us delighted Arduino enthusiasts.

Subscribe to How-Tos with Matt Richardson in iTunes, download the m4v video directly, or watch it on YouTube and Vimeo.

Short of scoring a spot on the ISS experiment docket, putting your scientific aspirations into orbit can be a bit tricky. Why not try crowdsourcing your way into space? ArduSat's barking up that very tree, asking Kickstarter contributors to help them get a Arduino CubeSat off the ground. Headed by NanoSatisfi, a tech startup operating out of NASA's Ames Research Center, the project hopes to raise enough funds to launch an Arduino bank and a bevy of open-source sensors into orbit. The payoff for backers? Access. Varying levels of contribution are rewarded with personalized space broadcasts, remote access to the space hardware's onboard cameras and even use of the machine's sensors to run experiments of the backer's own design. If all goes well, the team hopes to launch more satellites for the everyman, including a unit dedicated to letting would-be stellar photographers take celestial snapshots. Sure, it's far cry from actually launching yourself into the stars, but would you rather be a tourist, or a scientist? Check out project at the source link below, and mull over that for awhile.

ArduSat wants to put Arduino satellite, your experiments into orbit originally appeared on Engadget on Mon, 18 Jun 2012 04:02:00 EST. Please see our terms for use of feeds.

I wrote earlier this week about an applied electronic circuits course for our bioengineering majors that Steve P. and I will be designing over the summer, and how it will be designed backwards from the labs we plan to have them do.  That wasn’t quite an accurate description of our design process though, as the selection of the labs is based on more fundamental curricular goals.  I think that Steve and I have similar goals for the course, based on our discussions of it, but we’ve not tried to write them down formally yet.  I believe that we’ll need to do this for ABET, if the bioengineering program goes for full engineering accreditation.

I know that the EE Department wants the course to have a wider appeal than just to bioengineering majors taking it because it is (well, will be) required, as fluctuations in the cohort size for engineering majors has been large (biggest in computer science, which has been on a roller-coaster ride nationwide for the past couple of decades). The BME department chair, who is also the bioengineering undergrad director and main adviser, estimates a class size of 30–50 students if the course is offered this coming winter, and expects growth to 50–60 over the next few years.  The labs have room for about 20 students at a time, so this means 2 lab sections this year, growing to 3.  If we had a wider appeal, we might be able to pick up some computer science students, some game design students, or some Digital Arts and New Media (DANM) students, who are currently avoiding EE courses despite some interest in electronics because of the highly theoretical EE 101 course that is prereq to everything.  One problem with this broadening is that most of the potentially larger audience will not have been required to take the physics electricity and magnetism class, which I think is going to be an essential prereq.

Trying to put these two ideas, the need for more explicit goals for choosing labs and a wider potential market for the course, together, I came up with a possible theme for the class to guide lab selection and topics for the course:

Students completing this course will be able to design and build simple biosensors  for measuring chemical, electrical, or physical properties of biological systems (especially humans) and recording the measurements for computer analysis or interaction.

I still have to run this idea by Steve, and we’ll almost certainly need to tweak it a bit before we’re happy with it.  I’m particularly interested in two words in the goal (which I think Steve will agree with): design and build.  I don’t want this class to be a theoretical circuits course, in which students learn to formulate and solve large systems of linear equations, with no connection in their minds to any design problems.  I also want the students to learn to make things that they can take home, not just breadboard prototypes, though I may have to compromise a bit on this one, with most labs being breadboard only, and only one or two getting them to the next stage: a soldered prototype. Designing PC boards is probably beyond the scope of the class.

The labs I talked about in the previous post all fit within this theme:

• Skin conductance meter.
• Electrical field measurements in an electrophoresis gel.  This one is a bit of a stretch for the new theme, as electrophoresis gels are a standard lab tool, but not a biological system.
• Conductivity of saline solutions. Used for measuring ecosystems (like rivers).
• Do-it-yourself EKG
• Optical pulse detector
• Breathalyzer
• Thermistor-based temperature measurement.

Since that post I’ve come up with a couple of other ideas:

• Capacitance touch sensor (nice intro in Microchip application note AN1101).  This one is more ambitious than the EKG even, in that it involves a capacitance-sensitive oscillator design, but the oscillator is low frequency and the frequency sensing can be done by a microprocessor. They could use the same Arduino that they use for recording voltage data in other labs, but we’d have to provide them with a different program, since we are planning on having no programming required in the class or as prereqs to the class.  If the oscillator is a low enough frequency (say around 1kHz), then the program could be almost identical to the interrupt-driven data logger that my son wrote for the homemade super pulley, but interpreting the interrupt times differently.
• Potentiometer-based goniometer for measuring joint angles.  Like the thermistor lab, this one is mainly a voltage-divider lab. The design problems are more mechanical than electrical, but it would be useful for students in understanding noise problems in sensors, since potentiometers are notorious for the noise in the signals.  It would also prepare students well for later work (outside this class) using servos, since most servo motors use a potentiometer-based angle measurements in their feedback loop.  I wonder whether the guts of a servo circuit are within the scope of this class—probably not, as much of it is concerned with handling the power demands and voltage spikes of the inductive load of the motor.

There have been a few ideas that I’ve had to reject as being overly ambitious for a first circuits course or too expensive to implement:  anything involving a microscope or micromanipulator setup is too expensive (eliminating most of the nanopipette work done in Pourmand’s lab), anything requiring weeks of practice to set up is also out (eliminating much of the nanopore work in Akeson’s lab, since forming the bilayers is still an art that few master quickly, also eliminating most work that would require growing neural cell cultures).  The nanopipettes and nanopores also require measuring currents in the picoamp range, which requires very sensitive electronics and extreme attention to noise control (including doing everything in a Faraday cage), which is probably beyond the scope of a first circuits class.  A subsequent bioelectronics class could cover patch-clamp amplifiers and other specialized measuring circuitry.

We probably do want some lab that measures ionic current, though, as that is fundamental to both the nanopipette and nanopore work.  I wonder whether we can do a scale model of the nanopore (with pin-prick size holes in plastic or Teflon), so that the students can measure the currents without the picoamp scale problems.

I suspect that when we try out the labs, we’ll find that only about half of them work well for us, and that several of them rely on the same basic circuit ideas (like voltage dividers to convert resistance into voltage).  In the latter case, we may give students the choice of several different labs to do.  I’ve always liked the approach of giving students a number of different design problems (of roughly comparable difficulty and covering the same fundamental concepts) and letting them choose which ones to work on.  I’ve never implemented this approach in any of my classes, though, as I’ve either been faced with a pre-designed set of lab exercises that I didn’t have the authority or time to redesign or I’ve gone for quarter-long independent projects which are not even attempting equivalence between projects.

Whether we end up rejecting some of these labs or merging some into alternative choices for a single lab, we’re obviously going to need more lab ideas.  Does anyone have any?

CubeSats are nothing new – hundreds have been launched into Earth orbit by schools and universities over the past decade. Like anything cool, an Arduino eventually gets thrown into the mix. That’s what the folks behind ArduSat are doing: they’re launching an Arduino-laden satellite into orbit with a bunch of sensors to enable anyone to become a citizen space scientist.

On board the ArduSat is a suite of sensors including a spectrometer, Geiger counter, IR light sensor, electromagnetic wave sensor, a temperature sensor, gyroscope, accelerometer, magnetometer, GPS unit, CO2 sensor, and of course a few cameras. The rewards for this Kickstarter are fairly interesting: backers who pledge $500 are able to buy a week’s worth of time using the ArduSat sensors for your own personal experiment.

As for how this Arduino-powered satellite is getting a ride up to Low Earth Orbit, the team plans to send an application into NASA for the CubeSat Launch Initiative ride-along program. If NASA selects the ArduSat, it’ll get a ride into space along with other CubeSats on a larger commercial launch. If the ArduSat isn’t selected by NASA, the team behind this satellite has secured funding to piggyback on a commercial launch.

Tip ‘o the hat to [HackTheGibson] for sending this in.

We’ve seen many examples of floppy and hard disk drives being sequenced to make music, but the Moppy can be controlled by an external keyboard. Sammy1am created the Moppy using and Arduino UNO and some stepper motors to set the frequencing of the spinning disk drives.

[via Arduino Blog]

Dr. Scott Ananian, from the One Laptop Per Child (OLPC) project, conceived an Arduino Leonardo-compatible board especially designed for the OLPC XO laptop, with the goal to cut down its price as much as possible, to foster its adoption even in developing countries. From Scott’s blog:

The board uses mostly through-hole parts, with one exception, and there are only 20 required components for the basic Arduino functionality, costing about $5 (from digikey, quantity 100). It is reasonable for local labor or even older kids to assemble by hand.

The board, named XOrduino, is open hardware (schematics and pcb files can be found on github), and can be directly plugged into the XO’s USB ports, which allowed Scott to save the money required for the USB connector. Moreover, its design has been inspired by other open hardware projects, such as SparkFun’s ATmega32U4 breakout board and SparkFun’s Scratch Sensor Board-compatible PicoBoard.

Scott designed also a second board, which is even cheaper than the first one, called XO Stick:

It’s based on the AVR Stick using the ATtiny85 processor and costs only $1/student. It’s not quite as user-friendly as the Arduino-compatible board, but it can also be used to teach simple lessons in embedded electronics.

A longer description can be found here, while detailed release notes can be found on github.

It’s very exciting to see how open technologies, such as open hardware and open source software, contribute to the way education and creativity can take place around the world, especially regarding their promotion in developing countries.

[Via: Ossblog, OLPC blog, Scott Ananian's blog]

Arduteka en colaboración con Cooking Hacks y Milla Digital del ayuntamiento de Zaragoza han preparado un evento con capacidad para más de 400 personas en uno de los edificios más emblemáticos de la ciudad, el Antiguo Seminario Metropolitano de Zaragoza transformando en una moderna Ciudad Administrativa Municipal y que amablemente han cedido para organizar el evento.

Desde charlas sobre arte interactivo con Arduino como interface, pasando por talleres sobre impresión 3D hasta demostración de integración de Arduino con Asterisk será solo una parte de lo que vamos a poder disfrutar, ya que estarán habilitados diferentes Stands como el de Parrot, en que podremos probar el nuevo Ar-Drone 2.0, el de Cooking Hacks que nos amenizarán con micro talleres Arduino e incluso el de nuestros amigos de Ultra-Lab que seguro hará las delicias de los asistentes.

Por si esto fuera poco.. Contaremos con la presencia y colaboración de David Cuartielles, el cual nos ofrecerá una charla sobre los últimos productos Arduino que se está aconteciendo…

Accede ahora a toda la información en la nueva web de Arduteka AQUÍ e inscríbete!!

Te lo vas a perder??

Via | Arduteka