A Hall-effect sensor uses a semiconductor material to detect the presence or absence of a magnetic field. Because magnetic fields can penetrate many materials, the sensors do not require either direct contact or a clear optical path. So you can use them in situations where a switch might mechanically fail or a sparking switch contact could cause a fire or explosion. They also work in a somewhat dirty environment that prevents use of an optical switch. Hall-effect devices do require close proximity to a magnetic field, so you cannot use them to detect a distant magnetic field. Sensor manufacturers specify sensitivity in units of Gauss (G) or millitesla (mT). A Honeywell SS400-Series device, for example, has operating characteristics that range from about 70 to 200G, depending on the model chosen. According to Wikipedia, a typical "refrigerator magnet," the type used to hold shopping lists and family photos on the fridge door, has a field of 50G and a small neodymium (rare-earth) magnet has a field of about 2000G. See More ...

The GRASP Laboratory at the University of Pennsylvania has an interesting robotics program that deserves some attention. GRASP stands for general robotics, automation, sensing and perception, and the lab blends computer science, electrical engineering and mechanical engineering in a collaborative environment that lets students, research staff, and faculty work together on interesting projects. According to the lab's information, it has a $10 million budget that helps researchers build autonomous vehicles and robots, develop self-configuring humanoids, and create robot "swarms." See More ...

When you need a USB 2.0 connection to a human-interface device (HID), matching the specifications from the USB Implementers Forum with the USB port on an MCU can take a lot of time, code, and energy. Microchip has a new device that simplifies this type of connection and because the chip, MCP2210, will "look like" an HID, you just plug in a USB cable and it works. You also have a USB-certified connection to a remote SPI-based circuit. The Windows, Linux and Mac-OS operating systems all support the USB HID class of devices. See More ...

 The 24 January 2012 edition of the Wall Street Journal included an obituary for Norman Edmund, the founder of Edmund Scientific, who died at age 95. I ordered some components from Edmund while in high school and my dad and I stopped at the company's Barrington, NJ store during a trip to visit Drexel University in 1962. The store provided a lot to look at--telescopes, microscopes, scientific kits, lenses, books, star charts, and barrels full of optical components. I never got heavily involved with building telescopes or photography as a hobby--electronics and chemistry took most free time-- but always had an Edmund catalog close at hand. A project might involve something Edmund had in stock. For optics enthusiasts, Edmund provided a broad spectrum of components, finished products, and kits for schools and young experimenters. I would bet as kids, many scientists and engineers got a kit or a telescope from Edmund for a birthday or Christmas. See More ...

In mid January 2012, Design News magazine sponsored a 5-hour track--one hour per day for five days--dedicated to microcontroller basics. Although the live seminars have passed, you can find them archived on the Design News Web siteObjectives for each seminar. Each seminar provides about a 45-minute lecture with PowerPoint slides and streaming audio that includes a few questions and answers. You can find answers in the "chat" window for each session, too.  Here's the link to the list of available courses: www.designnews.com/lecture-calendar.asp See More ...