There is a major omission on page 1 in the ninth paragraph (cited below):
You can only reverse a DC motor if you reverse the polarity of either the armature .OR. field, but .NOT. both: Shunt wound, series wound and compound wound motors DC derive their field current from the voltage applied to the armature, meaning both are reversed simultaneously, and the motor will continue to spin in the same direction.
"The good news is that as we saw in Chapter 3… And if we want to motor or generate with the reverse direction of rotation, all we have to do is to reverse the polarity of the armature supply. The d.c. machine is inherently a four-quadrant device, but needs a supply which can provide positive or negative voltage, and simultaneously handle either positive or negative current.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.