In high school I helped record daily weather measurements from instruments on the second-story roof. We used readings from wet- and dry-bulb thermometers to determine relative humidity. A psychrometric chart let us read off the percent relative humidity value. Today, relative-humidity sensors make measurements directly and produce a voltage proportional to the percent relative humidity (%RH).

You might know Ramtron International for its ferroelectric random-access memory (F-RAM) devices that rely on ferromagnetic polarization in a thin film of crystalline material to store binary information. But the company has started to expand the reach of the F-RAM technology by including it in radio-frequency identification (RFID) devices, or tags. RFID tags are not new, but the characteristics of F-RAM combined with wireless communications will make them a top contender in applications that go beyond basic product identification and tracking.

In the previous blog entry, I described two ways to control, or commutate, brushless DC (BLDC) motors by using information from internal Hall-effect sensors or back-EMF signals from the motor windings. So you might wonder if one or the other control technique better suits an application you have in mind.

To find out, I talked with Scott Eckles, application engineer and Mike Moore, director of engineering at the Hurst Manufacturing division of Emerson Motor Technologies.

I reviewed the Renesas BLDC Motor Control Evaluation Kit and you can find the written and video reviews on the Evalkits.com site. Unfortunately, much of the high-level information about brushless DC (BLDC) motors can leave you wondering how they actually work.