As shown, we use 555 timer in the astable mode to get the required frequency and supply it to the IR LED. The operation of the timer is pretty straight forward. The relevant equation is given below

f=1/(0.693 x C2 x (R1 + 2 x R2))

The values I have given are just an example. You can try out different combinations so that you will be able to place resistors that are close to the calculated values(meaning, we dont get resistors with value 111Ω so choose the value carefully). The reisitors R3 and R4 are current limiters and the transistor 2N2222 is used as a switch. You may use any other transistor as a switch. Now, lets come to the tricky part

The LED will always need more cooling time. You cant pump in more current into the LED than what it can take. If you dont take care of that, the LED will overheat and will be spoilt or worse generate very high noise. Hence, be sure of the current it can take and set a suitable value to R4. of course you can calculate the current flowing through the LED by considering the branch from VCC-R4-transistor-LED-ground. Usually the drop across the transistor will be 0.2V (It depends on which transistor you use) and the drop across the LED is around 2V (Again it depends on your LED). So, 5V for VCC minus 2.2V which leaves 2.8V across the resistor R4. So, 2.8/47Ω ≈ 60 mA .

This is the same current that flows through you LED!! Simple right? Now, depending on your LEDs you can increase the current flowing. Varying R3 will increase the current too so you may use that to tweak your power. Also, you can send the 38kHz as bursts for short time. This will allow the LED to cool between bursts. By doing this, we can increase the current that is driven through the LED thereby increaing the power output. More power means, more range. But be careful NOT to send more that 125% of the rated current calue through your LED. A simple burst circuit may consists of two timers, one at 38kHz and other at 1kHz and these are given to AND gate. Hence, the output will be burst of 38kHz waves for 0.5ms(50% duty cycle). You can use 2 LEDs in the same circuit, but you need to decrease the resistance R4 appropriately. But more than 2 is not recommended.

Now lets look into the receiver part. TSOP is an IR receiver module. It has many series that work at 38kHz and 40kHz. Lets consider the 38kHz(Since I have used it, I am considering it. You may try the other receiver modules as well, there are plenty of modules available in the market).

Its a 3 pin IC as shown and the pin that is away from the other two is pin number 3. Pin 1 in ground and pin 2 is Vcc. Pin 3 is the output of the sensor which will be a logic 1 or logic 0. Please read the datasheet for more details. Anyways, this receiver IC makes our life much simple as we dont need to break our head to build a receiver circuit and get digital output from it. The simplest way to connect the circuit is as shown below

Simple right? Anyways, you need to orient your sensor and transmitter correctly so that you can receive the reflected wave efficiently. So, mounting is very important of both your LED and TSOP. The receiver has a directivity of 45°. So, you might want to see to it that you will keep it aligned as straight as possible. To use this IC efficiently, as mentioned earlier, use two timers and AND gate to send burst of signals. That will eliminate noise and the efficiency and accuracy of the receiver will improve. As said in the data sheet "After each burst which is between 10 cycles and 70 cycles a gap time of at least 14 cycles is neccessary." Hence, by sending bursts, you will be able to improve the range also. This circuit must give you a range of 30 cm from transmitter and receiver.

Any suggestions, corrections or queries please comment :)

I got interested in these temperature sensors after reading about the picaxe pongsat project on Hacked Gadgets

I did a little reading, and the pongsat project seems very interesting, and very cool. If anyone is interested in the pongsats, more info can be found at JPAerospace (the company that is making the free pingpong sized experiments happen)

Anyway, back to the Temperature sensor. I managed to pick up a few off 'ebay for a couple of dollars, and figured i should add one to my little kit of quick prototyping parts.

Following is a quick schematic, and sketch of the finished design.
Please note, the drawing of the board says "To Output", when its supposed to go to an input. it also means Pin0 on the schematic is possibly not suitable either (i used input 7 on a picaxe 18 for the code)

And, with this post, i figured i should start adding code to show how to use the parts that i am making. its very basic, as at the time of writing, I hadn't had a chance to play around with the probe. So here it is:

main:
readtemp 7,b1 ‘ read value of temp probe on input 7 into b1
debug b1 'display b1 on the picaxe programmer
goto main 'loop back to main

And thats it for another post,
Thanks for listening,
Matt

Things do not always go as planned.

I called to order and then didn't hear anything for a couple days.  The nice CSR told me that they were waiting on a Rx from my endo.  Um, what?!?!?  Turns out that Dexcom "changed their packaging" or something and they needed an updated letter of medical necessity.  I instantly paled at the thought that my sensors would no longer be covered and I'd have to jump through a million hoops to get them back.

It took an awfully long time to contact my endo (they don't have a number that goes straight to a person, only a line where you can leave a message) to know if they faxed the form.  Then an awfully long time to get confirmation from EdgePark that they were sending my sensor.  They were able to ship one box, then it looks like I will get a 90 day supply after that.

I stretched my penultimate sensor as long as it would go, but I eventually had to switch to my very last one.  I have been extra careful with it to make sure it lasts until my new sensors arrive.  I finally got the tracking information today and the new sensors arrive tomorrow.  Today was day 7 with my last sensor, so they are cutting it awfully close...

A team from Massachusetts Institute of Technology (MIT) is looking to see if it is possible to harness the extremely small electrical current generated by trees could be used to recharge sensors' batteries.

The researchers said that the US Forest Service currently predicted and tracked the path of fires by using a variety of resources.

One key tool used by the Forest Service was remote automated weather stations, but these were expensive and sparsely distributed.

Additional sensors could be installed to improve coverage, they added, but the batteries needed to be recharged or replaced manually.

The team hopes their design will be able to trickle charge the remote sensors' off-the-shelf batteries, and provide enough electricity to power temperature and humidity sensors.

The scientists suggested that the system would be able to harness enough tree power to allow the sensors to transmit data four times a day, or immediately if there was a fire.

They explained that the signal would "hop" from one sensor to the next until the information reached an existing weather station, which would then beam the data via satellite to a forestry command centre in Idaho.

The electrical current is produced by an imbalance in pH between a tree and the surrounding soil.

The sensor network, which is being developed by Voltree Power, is set to be tested on a 10-acre (four-hectare) plot owned by the Forest Service in Spring 2009.

Source: MIT press release
Date: 22/09/2008

Yesterday we linked to an OCZ Neural Acutator Interface teardown. Several in the comments wanted to know more about the sensor electrodes. Check out the OpenEEG project and OpenEEG mailing list for information on sensing, amplifying, and recording brain activity (EEG). The OpenEEG project maintains an open source Simple ModularEEG design. Two other open source variants of the ModularEEG are the MonolithEEG and [Joshua Wojnas'] Programmable Chip EEG BCI. All three projects use Atmel microcontrollers, with designs in Cadsoft Eagle.

Brain activity is measured using passive or active electrodes. Passive electrodes require a conductive paste to make proper contact with the skin (examples: 1, 2). Active EEG sensors don't need conductive goop because they have an amplifier directly on the electrode (examples: 1, 2, 3).

[via anonymous reader, comments]

If you are in London this December 28th & 29th you can be amongst the first people in the UK to play Mindball at the Science Museum.Mindball is one of the first examples of entertainment using brainwaves to control the content, in this example a ball in a game.

Competitors are hooked up to an EEG (Electroencephalogram) machine, which reads their brainwaves and transfers them to a physical movement of the ball. The more stressed you are, the easier it would be for your rival to push the ball to your side and ultimately over the line to score a goal.

Its all very reminiscent of Firefox (the film not the web browser).

The 7th Spanish Conference on Electron Devices brings together the work of both research groups and companies on the field of electronic devices. This edition will take place in Santiago de Compostela, carrying on with a series of previous events in Barcelona (1997), Madrid (1999), Granada (2001), Calella de la Costa (Barcelona, 2003), Tarragona (2005) and El Escorial (Madrid, 2007).

The Conference program consists of invited and contributed papers organized in topic sessions. Contributed papers accepted for the Conference will be presented either orally or by poster and they will be published with ISBN, subsequently appearing in the XPLORE IEEE database. Therefore, papers must be written in English and follow the proposed format. There will be prizes for the best posters and oral presentations.

Typical topics include:

Materials, technology and process simulation.
Device modelling and simulation.
Characterisation and reliability.
Sensors, actuators and MEMS.
Photovoltaic and optoelectronic devices and displays.
Micro and nano-devices.
RF, microwave and power devices.

http://www.ac.usc.es/cde09
http://www.cde-conf.org

So, I've been thinking a lot about goals for this and other classes this term. One project that I've started working on in preparation for either this class, or for CART 451 are wireless sensor modules for use in interactive installations.

Essentially, I intend to prototype a circuit that will house an Arduino-ready Atmel168 micro-controller, with an ESKI SM-100 wireless transceiver, and 6 possible sensor inputs. The idea is that one could spread out several of these sensor modules throughout a space, and they would all "speak" to a single receiver that could interface with a larger computer, that in turn could control various projectors, sound modules, on a single display through softwares such as processing or Jitter.

At this time the board design includes:

• connection ports for FTDI to permit on-board reprogramming of the Atmel Chip,
• a wide-angle ultrasonic range finder,
• a three-axis accelerometer,
• *five additional inputs for analog sensors (inputs accommodate both 3-pin & 2-pin connections),
• **a battery pack connector,
• an AC/DC power connector.

( *The accelerometer requires one port for each axis of the accelerometer. A series of switches will permit one to shut down the accelerometer completely, or to select data from specific axises to be sent. Each axis used requires one of the five "additional inputs", therefore if the accelerometer is on and reporting results of all 3 axises, there will be only two free ports available for additional sensors. )

( **At this point, I have not yet completed tests on a breadboard with all the components functioning together, and therefore do not know how much current is required to run all components simultaneously. This will be a serious concern in attempting to power the module without an AC/DC wallmart adaptor. )

The board is being designed in Eagle CAD software to facilitate production of 5 or 6 sensor modules and 1-2 receiving modules depending on budget and time.

The board is designed to be somewhat upgradeable; the Atmel Chip will be removable, as will the ESKI SM-100 radio and the ultrasonic rangefinder, in the event that any parts are damaged and need replacing. This, along with keeping other ports free for a selection of sensors, is done in order to keep the module itself modular, so that it is versatile, easily reusable, and as a result more environmentally friendly -- as there is no need to get rid of an entire module should something go wrong, or produce new modules for each new project conceived of. (Unfortunately, in an effort to keep the module relatively compact, so far, the accelerometer will be fully integrated, and not removable -- hence the switches).

I will post an image of the circuit when it is completed. ( I am currently trying to locate proper switches for the accelerometer connections, and compatible Eagle footprints to complete the board.) As soon as it is completed, the design will be sent out to be produced in an effort to have a prototype ready by mid-term.

The ultimate goal of this project is to then be able to use these modules for interactive installations. The receiving station will be able to make use of whatever data is required to produce reactions in an environment, based on whichever sensor outputs are deemed useful for a specific project. Therefore, I am essentially, at this point, trying to construct a tool, that will later facilitate (or at the very least be a large step ahead in) the production of a responsive installation or environment.

The seven-digit display enables high resolution to be achieved when used with long absolute displacement transducers and even higher resolution when precise positioning or measurements are required. Data logging of up to 10,000 readings is available, and other functions include peak hold, presets, simple mathematics and max-min values. The menu-driven display makes setting up and operating the instrument easy.

Solartron's extensive and continually growing range of digital probes, linear encoders and analogue input modules are all compatible with the SI 3000, as are the company's LVDT, half bridge, dc, 4-20mA displacement transducers. Ametek Gemco 4-20mA magnetostrictive transducers can also be used. The SI 3000 series can accept inputs from other types of DC and 4-20mA transducers, for example, pressure, force and temperature or third party LVDT transducers.

Outputs include DC, 4-20mA and RS232 interfaces. The units are ideal for use in an extremely wide range of industries, including automotive, aerospace, steel production, process automation, as well as the test and measurement sector. Where more channels are required, Solartron offers the higher specification SI 7500 controller, which can accept up to 16 digital probes or modules. This advanced model provides SPC support and offers a suite of mathematical functions.

AIBO
When electronic communication giant, Sony launched the Artificial Intelligence roBOt dog (AIBO) in 1999, the pooch was regarded as a breakthrough in the robot entertainment market. Since then, AIBO (meaning "love" or "attachment" in Japanese) has sold over 130 000 units worldwide. AIBO is the first generation of artificial intelligence pets designed to learn and adapt to its environment.

These automatons can communicate over wireless networks and even photograph things they ‘see’ and post these to their personal (owner’s) websites. He will wag his tail when patted on the head, and, if you're lucky, he'll produce an affectionate high-pitched squeal. The robo-pup can respond to voice commands, pick up his AIBOne, and play with his balls just like a real dog.

However, Sony has discontinued production of AIBO since 2006 following profit erosion from Apple iPods, and technical support for existing AIBO’s ends in 2013. They were pricey anyway – at a local retail price of about R15 000.

NABAZTAG
Meet Nabaztag - a 23 cm tall WiFi-enabled electronic bunny. Nabaztag (meaning “rabbit” in Armenian) is considered as a 'smart object' and can connect to the Internet (to download weather forecasts, report traffic jams, read its owner's email etc) and is also fully customizable and programmable.

Nabaztag can also send and receive MP3s and messages and read the latter out loud in up to 16 different languages. He can also use his digital voice box (or indicative lights) to deliver weather forecasts, stock market reports, news headlines, e-mail alerts, RSS-Feeds, MP3-Streams, and he can be your alarm clock.

Some Nabaztag owners have joined social networks to share photos and videos on websites like Flickr and YouTube. Users can also create and share podcasts (or rather ‘Nabcasts’) and add to the growing collection online.

The latest version Nabaztag has a microphone that allows for voice activation of some of its services. A final added feature is a built-in RFID reader to detect special-purpose RFID tags and the ability to identify objects. Nabaztag can even use these RFID tags to read special edition versions of French children's books.

PARO
Paro has got to be the cutest and most lifelike of all the artificial pets. While the others resemble animals in suits of armor, Paro the baby harp seal is specifically designed to be cute and cuddly, and make people feel comforted.

He is what is known as a Mental Commitment Robot - developed to interact with human beings and make them feel emotional attachment. These robots are specifically aimed to trigger subjective evaluations and have shown to have positive psychological, physiological (such as improvement in vital signs), and social effects among inpatients and caregivers young and old.

Paro has five kinds of sensors, which are a little different from the familiar five senses belonging to the living. He uses tactile, light, audition, temperature, and posture sensors, with which it can perceive people and its environment.

The light sensor allows Paro to recognize light and dark. He feels being stroked and beaten by tactile sensor, or being held by the posture sensor. Paro can also recognize the direction of voice and words such as its name, greetings, and praise with its audio sensor.

Like AIBO the wonder-dog, Paro can learn to behave in a way that the user prefers, and to respond to its new name. If he is beaten for bad behaviour for example, the action is recorded to memory and the robot seal will perform less of the deviant behaviour in the future.

PLEO
Pleo is a 'designer species' type of pet robot that begins life as a newly-hatched baby Camarasaurus. Like the others robo-pets, he is said to incorporate all the basic traits of autonomous life and is specifically engineered and enhanced to mimic life and relate to his owner on a personal level.

Pleo was engineered by a group of robotics specialists, animators, technologists, scientists, biologists, and programmers who noted the biological and neurological systems of the Camarasaurus, and "re-interpreted" those elements through hardware and software. The design combines sensory, articulation, and neuronetics to create a lifelike appearance with organic movement and adaptable behaviors.

The dinosaur is equipped with senses for sight, sound, and touch, and learns and reacts to sensory stimuli as it explores its environment. Interaction with the environment has subtle effects on its behavior, and every Pleo eventually exhibits a unique personality.

Two or more Pleos can recognise one another, and marketers claim that they can even transmit colds to each other. However, unlike real organic pets, Pleo wont ever die on you or run away. So long as technical support is available, he and his different species of robot friends – AIBO, Nabaztag and Paro, will live forever.

SOME PHILOSOPHICAL THOUGHT
It is difficult to say how the general public will respond to the rising popularity of artificial pets such as these. A few years ago, Tamagotchi had children and adults obsessed with caring for pixelated, black and white digital dogs or dinosaurs. Some owners really believed that these had real, humanlike personalities and were inconsolable when their virtual pets' lives ended tragically.

Dr Hannah Slay, owner of a pet AIBO, doesn't see anything particularly wrong with owners becoming emotionally attached to robotic pets. She feels that they could have real benefits for the sick and the lonely. A study by Cambridge University suggests that real pets can reduce stress, encourage exercise, reduce blood pressure and cholesterol, and stave off loneliness.

"If AIBO can do that then I don't see anything unethical about it"
 - Dr Hannah Slay

Rhodes University philosophy lecturer, Francis Williamson remains skeptical about humans building relationships with artificially intelligent pets. He suggests that products like AIBO merely provide the appearance of a relationship rather than an actual one.

"Any good consequences of such an invention are based on an illusion" - philosopher Francis Williamson

In other words, people are being duped.

I personally don’t see anything wrong with people becoming emotionally attached to robot pets, although I would never want to own one. Even if a cuddly Paro looked happy to see me, the fact that it wouldn’t be sincere about it would put me off. But if they can dupe others and make them happy as a result then that’s dandy.

Human beings have been conditioned by the media to perceive personality and consciousness in things that don’t actually have them. Think about all the people that believe their teddy bears, cars and household plants have personalities. Although robot pets are very far from being self-aware and conscious, at least they are more fun and lively than a mute, plastic pooch.

I leave you with one of my favourite quotes by sir Stephen Fry:

"If ignorance is bliss, why aren’t there
more happy people in the world?"

Interesting Links:
Top-selling robot pets
What’s the point of robot pets?
Bye Bye Rover – AIBO article and video

The proposed actuator consists of active structures that are precisely controlled by novel piezoelectric nanofibers. The functional principle of the proposed actuator is unique in that it can provide a dynamic shear force on blood clots in vascular arteries. This shear force can be fine-tuned to facilitate the separation of the blood clot from the wall of the vascular artery due to the shearing-thinning phenomenon, thus enabling complete retrieval while minimizing the risk of damage to the arteries.This research will contribute new fundamental knowledge in the areas of piezoelectric response of nanomaterials as well as the mechanical behavior of blood clots.

Dr. Shi, the Principal Investigator, has been an assistant professor in the Mechanical Engineering Department at Stevens Institute of Technology since 2004. He obtained his M.S and Ph.D in 2001 and 2004 respectively from Massachusetts Institute of Technology. His research interests include functional nanofibers and nanocomposites, micro/nano actuators and sensors, RF, Bio, medical MEMS/NEMS systems design, modeling and fabrication . He won the ASNT fellowship from the American Society of Nondestructive Testing in 2007 for the development of a nano acoustic sensor. Shi is also a member of several scientific and professional societies, including IEEE, MRS, ASME, and Sigma Xi.

Co-PIs working with Professor Shi on the project are Professor Sundeep Mangla (M. D., Director of Interventional Neuroradiology , Associate Professor of Radiology, Neurosurgery, and Neurology ) and Professor Ming Zhang (M.D, Assistant Professor, Dept of Anesthesiology), both from SUNY Downstate Medical Center at Brooklyn, New York.

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About Stevens Institute of Technology

Founded in 1870, Stevens Institute of Technology is one of the leading technological universities in the world dedicated to learning and research. Through its broad-based curricula, nurturing of creative inventiveness, and cross disciplinary research, the Institute is at the forefront of global challenges in engineering, science, and technology management. Partnerships and collaboration between, and among, business, industry, government and other universities contribute to the enriched environment of the Institute. A new model for technology commercialization in academe, known as Technogenesis®, involves external partners in launching business enterprises to create broad opportunities and shared value.

Stevens offers baccalaureates, master's and doctoral degrees in engineering, science, computer science and management, in addition to a baccalaureate degree in the humanities and liberal arts, and in business and technology. The university has a total enrollment of 2,040 undergraduate and 3,085 graduate students, and a worldwide online enrollment of 2,250, with about 250 full-time faculty. Stevens' graduate programs have attracted international participation from China, India, Southeast Asia, Europe and Latin America. Additional information may be obtained from its web page at www.stevens.edu.

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