A.Khan asks:
“I am trying to use IR sensors to detect where someone is sitting in a room. The IR sensor would be placed on a rotating panel where it will send signals to the microprocessor about where it detects people sitting and the microprocessor can then plot in the 360 circle at which angles it received the input.
For this, what do you suggest is the best way to go? I was thinking more about getting IR body heat sensors premade components (~$6-$10) which give out high or low processed signals when they detect heat and sending it off to an arduino board. But it looks a bit on the expensive side. Is there anyway of creating this setup cheap?
Thanks.”
What a fun question!
I spent the past couple of days coming up with what I think would be viable solution to your problem. To start, Adafruit happens to offer a great little PIR that, as you suggested, responds with a high/low signal in correlation to a IR source crossing its path. Adafruit’s PIR also has a 120 degree viewing angle, which is a bit wide if you are trying to pinpoint a person in a room. Because the device relies on the “path” state to change between the two sides of the sensor and you want to pinpoint a heat source, you will have modify the sensor to limit the viewing angle. You can do this by removing the faceted Fresnel lens and attaching a small tube about 1″ long over the sensor or by covering a percentage of it with some non-transparent tape (this certainly would require some experimentation). Ladyada has a wicked tutorial about PIRs work and how to modify/use it.
The next problem is the fact that you want to view in 360 degrees. I came up with three solutions for this. First, which is the most costly, would be to make your circuitry wireless, relaying the data back to a server. This also poses the problem of powering the device. The second would be to keep the sensor tethered and sweep the device clockwise then counter clockwise. Finally, the third, would be to follow the attached diagram. I had the idea that if you used an 1/8″ stereo “headphone” plug & jack you could simulate a slip-ring (commonly found in wind turbines to transfer electrical energy from the generator in the rotating nacelle). This would allow you to isolate the PIR on a rotating platform and transfer signal/power to the device without interruption. You might want to add a little non-conducting grease to the interface to keep it from wearing out.
In order to make the device rotate, I would recommend using a stepper motor attached to a larger gear, which acts as a yaw bearing for the PIR platform. You can easily control the stepper using an H-bridge (for bipolar) or darlington array (for unipolar) to precisely cover your 360 degrees. Now you get to do the math to determine how many steps per rotation, decoding the PIR, etc.
I hope this answers your question! Up next is J.Miraldi with a question about creating a robotics program for their high school!
Don’t forget, everyone is invited to ask a question:
Click here!
NEW PRODUCT – Clear flip-top storage box. For securely storing small “anythings” (electronics, SMT/SMD components – whatever you need to store) this clear plastic box is a great general purpose flip-top & snap storage box. The snap is sturdy and will not break off. The internal dividers are removable.
- Number of compartments: 12
- Size of compartments: 1.7″ x 2.3″ each
- Size of box: 10.2″L x 4.7″W x 1.6″H
In stock and shipping now!
Have you ever had a pin on a 0.1″ header that you just couldn’t get to reflow properly, especially with lead free solder (which requires a higher temperature to work with)? If so, it was almost certainly a GND pin connected to a large GND plane. The problem is that the GND plane dissipates a lot of the heat from the soldering iron. You can try using a much larger tip (larger tips do a better job of conducting heat that small ones), and/or you may need to jack the heat up quite a bit, but sometimes it just won’t reflow well to form a solid joint. The solution is easy, but you need to keep the problem in mind when designing the PCB. (more…)
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NEW PRODUCT – 5V 10A switching power supply. This is a beefy switching supply, for when you need a lot of power! It can supply 5V DC up to 10 Amps, running from 110V or 220V power (the plug it comes with is for US/Canada/Japan but you can use any plug adapter for your country, or just replace the cable with a standard figure-8 cable)
The output connects to a 2.5mm DC plug but its a ‘springy’ type so you can use it in 2.1mm jacks as well. There’s a green LED indicator lamp as well.
These will be great for people who want to power 5V LED strips or a lot of motors for a CNC project. Using a separate supply like this can be easier than trying to modify an ATX power supply as its smaller, quieter and has a plug on it ready to go!
- 5V up to 10A output
- 110V-220V input
- Comes with 2-prong US/Canada/Japan – for other countries use a basic plug adapter. 112cm (44in) long cable
- 2.5mm output plug, but will also work with 2.1mm. 110cm (42in) long cable
- Body size is 5.5″ x 2.4″ x 1.3″ (14cm x 6 cm x 3.3 cm
- Weight: 0.925 lb / 420g
In stock and shipping now!
Programming prodigy passes away at 16: Hear her philosophy of life -
Arfa Karim Randhawa, the computer programming prodigy who became the world’s youngest Microsoft Certified Professional at 9 years old, has passed away at the age of 16, according to reports out of her native Pakistan this weekend.
…As you’ll hear at the end, Arfa at 10 years old had also settled on her philosophy of life, and committed it to memory. She told me about it after our interview, when she was having her picture taken outside, so I turned my recorder back on and asked her to repeat it for me on tape.
“If you want to do something big in your life, you must remember that shyness is only the mind,” she said. “If you think shy, you act shy. If you think confident you act confident. Therefore never let shyness conquer your mind.”
Sad story, but also filled with hope and inspiration.
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NEW PRODUCT – CR2032 Lithium Coin Cell Battery. A perfect match for our sew-able coin cell holder. This non-rechargeable coin cell is CR2032 sized: 20mm diameter, 3.2mm thick. It has a nominal voltage output of 3V (although it starts a little high at 3.2V and slowly drifts down to 2.5V as it is used. The capacity is 220mAh assuming a draw of constant 3nA. For other drain rates the capacity may be reduced, check the datasheet!
In stock and shipping now.
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If you’ve ever tried to make a footprint in Eagle with more than one GND, VCC, VDD, NC, etc., pin, you might have noticed that you can’t have two pins with the same names, and you ended up having to name all your GND pins GND1, GND2, GND3, etc. If you’re mildly OCD like me, this is irksome, but thankfully there’s an easy workaround to this in Eagle. When defining your schematic symbol and naming each pin, rather than naming pins GND1 take the common name that you want to appear in your schematics and append it with @n. For example. GND@1, GND@2, GND@3. This ensures that each pin has a unique name, but they will all render as GND when placed on your schematic. Read on to see an image of the the schematic symbol defined for the power pins above (an LPC4350 for the overly curious). (more…)
[Editor's note: This is a post from our education blogger Adam] I have created a preliminary shield that allows for the interface of both analog and digital Vernier (www.vernier.com) sensors to the Arduino. The main idea is that an Arduino is significantly cheaper, and in my opinion more effective, then “black box” interfaces. Not to mention that using an Arduino opens the door to having the students explore just how sensors work.
So, please take the following survey and let me know what you think!
——>LINK<——
First of all, Happy New Year to everyone in the OSHW community! 2011 has been an amazing year, and I look forward to everything 2012 has to offer as the community continues to mature and develop.
One of my main resolutions for 2012 was to improve the way that I design, test and document most of the boards I work on, particularly where sensitive analog and high-speed parts are concerned (op-amps, high-resolution ADC inputs, SDRAM, etc.).
This desire to improve in these areas is the result of a number of things, but one of the main reasons is the unique challenges and constraints of OSHW. Unlike the traditional HW development models, OSHW implies working with or for a larger community in a relatively transparent way. Your audience isn’t just a consumer base purchasing a functional black box, but a wide spectrum of people with varying skills and experience who need to understand not just what a product does, but how the inner workings of it fit together to make it all tick. (more…)
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I have spent the past 6 years working with teams of high school students to design, build and fly what will be historys first high school satellite, TJ^3Sat. What started out as the dream of a former student, has turned into the hardest project I have ever had the opportunity to work on and the most educationally meaningful experience for my students.
The projects primary mission is to give any educational institution, K-12 and beyond, the opportunity to communicate and manipulate an actual satellite from within the classroom. The satellite contains a voice synthesizer, which when paired with our web interface, will allow for multi-lingual transmission of user submitted voice messages from low earth orbit.
Currently we are preparing to go into our testing phase, which will verify the satellite is fit for flight and we are manifested for launch on NASAs CRS-2 mission in 2012. In addition, we are in the process of making all of our materials available to the public; including PCB designs, code, presentations, and documentation. So that hopefully, this project wont be the last.
Check out the links and I hope you see just how important this community is to inspiring students and teachers alike. And please feel free to ask questions!
So keep those soldering irons warm and Happy New Year!
Adam
P.S. We will be flying Arduino
Links:
http://tj3sat.wikidot.com
http://www.popularmechanics.com/science/space/nasa/nasa-to-launch-the-first-satellites-built-by-high-school-students?click=main_sr
http://www.youtube.com/results?search_query=tj3sat
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NEW PRODUCT – Alkaline AAA batteries – 2 pack. Battery power for your portable project! These batteries are good quality at a good price, and work fantastic with any of the kits or projects in the shop that use AAA’s
These batteries are Alkaline (MnO2) chemistry, with a voltage range of 1.6V (fresh) to 0.8V (dead). The mAh capacity depends on discharge usage but at 25mA rate it is 1200mAh (check the datasheet in the download tab for more details)
These work perfectly with the Drawdio kit, Geiger counter kit, Brain machine kit, Ex330 multimeter, and 4xAAA EL wire/tape/panel inverter
In stock and shipping now.
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NEW PRODUCT – Panel Mount 2.1mm DC barrel jack. This power jack is designed to easily attach to a panel up to 8mm thick (0.315″ or 5/16″) and fit 2.1mm power plugs snugly and securely. Perfect for adding a power connector to your project enclosure. We like this jack in particular for its long body (so you can use it on thicker wooden panels), sturdy PCB spacer with 3 easy-to-solder eyes and ‘forgiving’ plastic lip that hides the drill hole.
In stock and shipping now!
Mini Thermal Receipt Printer Tutorial! Add a mini printer to any microcontroller project with this very cute thermal printer. Thermal printers are also known as receipt printers, they’re what you get when you go to the ATM or grocery store. Now you can embed a little printer of your own into an enclosure. This printer is ideal for interfacing with a microcontroller, you simply need a 3.3V-5V TTL serial output from your microcontroller to print text, barcodes, bitmap graphics, even a QR code!
Read more!
NEW PRODUCT – Mini Thermal Receipt Printer Starter Pack. Hit the ground running (and printing!) with this starter pack that includes a thermal printer and all the extras and save a few dollars while you’re at it.
Includes:
We really like this printer because its easy to make Bold, underline, inverted text, variable line spacing, left/center/right justification, barcodes in 11 standard formats with adjustable height, and even custom bitmap graphics.
Of course, we wouldn’t leave you with a datasheet and a “good luck!” – We have a full tutorial and matching Arduino library that demonstrates the following:
- Printing with small, medium and large text
- Bold and underline text
- Inverted text
- Variable
line
spacing
- Left, center and right justification
- Barcodes in the following standard formats: UPC A, UPC E, EAN13, EAN8, CODE39, I25, CODEBAR, CODE93, CODE128, CODE11 and MSI – with adjustable barcode height
- Custom monochrome bitmap graphics!
- How to include a QR code
In stock and shipping now!
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NEW PRODUCT – Mini Thermal Receipt Printer. Add a mini printer to any microcontroller project with this very cute thermal printer. Thermal printers are also known as receipt printers, they’re what you get when you go to the ATM or grocery store. Now you can embed a little printer of your own into an enclosure. This printer is ideal for interfacing with a microcontroller, you simply need a 3.3V-5V TTL serial output from your microcontroller to print text, barcodes, bitmap graphics, even a QR code!
This package comes with a thermal printer including the print head (it does not require ink, a set of power and data cables, and two plastic shims for panel mounting. Thermal paper not included! The printer uses very common 2.25″ wide thermal paper, available in any office or stationary supply store. It can fit up to 50 ft of paper in the bay at once. You will also need a 5 to 9VDC regulated power supply, that can provide 1.5A or more during the high-current print – our 5V 2A power supply will work very nicely. We also suggest picking up a roll or two of 50′ long thermal paper, and also a 2.1mm jack terminal block adapter which will make it easy to connect the power adapter. We also have a starter pack that includes all the above
We really like this printer because its easy to make Bold, underline, inverted text, variable line spacing, left/center/right justification, barcodes in 11 standard formats with adjustable height, and even custom bitmap graphics.
Of course, we wouldn’t leave you with a datasheet and a “good luck!” – We have a full tutorial and matching Arduino library that demonstrates the following:
- Printing with small, medium and large text
- Bold and underline text
- Inverted text
- Variable
line
spacing
- Left, center and right justification
- Barcodes in the following standard formats: UPC A, UPC E, EAN13, EAN8, CODE39, I25, CODEBAR, CODE93, CODE128, CODE11 and MSI – with adjustable barcode height
- Custom monochrome bitmap graphics!
- How to include a QR code
In stock and shipping now!
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Printable catalog (PDF)
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