This Christmas I finally found time to finish the Arduino based “ambient computing” project I started last year. The idea is that there are lots of tiny pieces of information on the web that are useful enough to deserve a dedicated, unobtrusive display like a clock or calendar.
A special thanks to everyone who stopped by our weekly “ask an engineer chat” – we’ll be back next week (Saturday, September 12th at 10pm ET). Congrats to “ongissim” who won the trivia contest “What was Adafruit’s first kit” – the answer was “The MiniPOV 2“. For 2 weeks in a row we’ve had perfect video and sound, next week we’re going to work on saving a chat log – we think the best way is to log via an IRC client since Ustream seems to support IRC (most folks use the Flash chat though). If anyone has any expertise or suggestions, post’em up in the comments!
Stop by our weekly “Ask an engineer chat” 10pm ET tonight (Saturday)… we’ll answer your questions about electronics, have a live web cam so you can see what we’re up to and we’ll have a special prize/giveaway at the end of the chat! Visit our Ustream channel at 10pm ET.
We all love USB. It is well supported across many platforms, easy to work with, and even able to provide a little power to the peripheral. However, the quirk of USB is that peripheral must share ground line with the host. The host is usually a PC and very often a desktop, which means it’s USB ground is electrically connected to earth ground in the wall outlet. It works fine most of the time, but not always.
Sometimes we prefer our ground separate. It happens when PC/earth ground is too “dirty” and we don’t want our circuit to pick up this dirt. Sometimes our device’s ground is not too good or even dangerous if connected to earth ground. Sometimes we are fighting ground loops. In any of this cases we want our USB isolated from the host.
Isolation improves common-mode voltage, enhances noise rejection, and permits two circuits to operate at different voltage levels. It also saves equipment (sometimes), especially PC-based measurement instruments like USB oscilloscopes, logic analyzers, as well as PC itself. It is also very useful in industrial setting, that probably why industrial USB isolator solutions cost between $200 and $400. While looking for a solution for my lab, I found interesting USB isolator part, recently released by Analog Devices, and decided to give it a try.
Labor Day is a United States federal holiday observed on the first Monday in September (September 7 in 2009).
The holiday originated in Canada out of labor disputes (“Nine-Hour Movement”) first in Hamilton, then in Toronto, Canada in the 1870s, which resulted in a Trade Union Act which legalized and protected union activity in 1872 in Canada. The parades held in support of the Nine-Hour Movement and the printers’ strike led to an annual celebration in Canada. In 1882, American labor leader Peter J. McGuire witnessed one of these labor festivals in Toronto. Inspired from Canadian events in Toronto, he returned the USA, to New York and organized the first American “labor day” on September 5 of the same year.
The first Labor Day in the United States was celebrated on September 5, 1882 in New York City. In the aftermath of the deaths of a number of workers at the hands of the US military and US Marshals during the 1894 Pullman Strike, President Grover Cleveland put reconciliation with Labor as a top political priority. Fearing further conflict, legislation making Labor Day a national holiday was rushed through Congress unanimously and signed into law a mere six days after the end of the strike. Cleveland was also concerned that aligning a US labor holiday with existing international May Day celebrations would stir up negative emotions linked to the Haymarket Affair. All 50 U.S. states have made Labor Day a state holiday.
Enjoy your 3 day weekend if you’re off next week, make something amazing!
Pluses Frankly I liked almost everything about this kit. Unlike most kits which just dip your toes in something this one really gives you what you need to dive in, go off on your own and start making stuff.
Versatility. Other kits come with a few LEDs a button and a photoresisor and the number of different things you can do is limited. This kit comes with tons of inputs and outputs, enough that you can easily remix them into your own gadgets easily without buying extra parts. Among other experiments I built my Comfortableness Measuring Instrument. But I’m sure you can come up with something better.
Breadth. Although there are only 11 projects in the manual, they each have several variations to experiment with, and each covers a useful component. Especially standout was the relay and shift register projects which were clearly documented and I haven’t seen them covered in other kits.
Just the right skill level. At least it was for me. I think you’ll probably want to know at least a little bit of programming–any programming will do– and a very basic understanding of electronic components. If you don’t have both of these I’d recommend the Getting Started with Arduino book which gets you up to speed pretty easily on both programming and basic electric theory.
Great manual. What you’re doing, how you’re doing it, troubleshooting and extending what you’ve just done. It’s very concise, but it anticipates problem spots and documents them well. For each project you get both circuit diagrams and graphics showing what should go where.
Digital footnotes. If you feel that the manual doesn’t cover a subject thoroughly enough there are usually shortened URLs to more information, code examples, full Wikipedia articles, and more.
Nicely self guided. You can do most chapters in 10-20 minutes to do most chapters. Or half a day if you get curious and go exploring on your own.
Quality components. They aren’t deluxe, but they’re not the cheapest they could have used. And they didn’t need to include the nice parts box or the acrylic holder but they did.
USB powered soldering iron, this scares us a bit – beyond possibly damaging your computer we can’t imagine it has good thermal properties (but if someone has another point of view, post up in the comments). The most you can get out of a USB port is 5V * 1amp (yes you can get 1 amp before the fuse blows) so thats 5W. We usually suggest 25 W irons to prevent cold solder joints and lifting pads.
Normally, a power component like this would have a big pad and some heat dissipation space under the heat slug. It might even have thermal vias going to another heat pad on the back side of the board. If it’s being run at anything close to it’s full current capability, that would be a requirement. This one is probably a bit underutilized though, rendering the big pad un necessary. It’s still a good idea for mechanical strength, but in the prototype world, we don’t always follow the rules
The problem here though, is that the open vias under the part can short to the thermal pad. That’s bad mojo. Some board fab houses can put a solid coat of mask over the vias and they’ll be okay. Not all board houses will do that though, and if the board has a silver finish (this one is HASL), you wouldn’t want the vias sealed because silver vias can outgas and corrode if completely sealed.
“Blockhead Stem is the sturdiest stem you’ll ever meet. A solid chunk of aluminum machined with sharp edges and corners, this stem is not for everyone. Ride it at your own risk.” And it’s under an open hardware-non-commercial type license, very interesting!
Printable catalog (PDF) or (EPUB)
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