This lab’s all about current events

Everything’s about connections.

On Monday, electrical engineering students in Dr. Michael Prairie’s Electronics II lab connected transistors to build postage-stamp-size amplifying circuits, similar to ones a guitarist might find in the amplifier that makes string-bending note sequences and prolonged riffs louder.

Simply speaking, an amplifier can be an electrical circuit contained within another device or a separate piece of equipment. An amplifier’s amplification is measured by its gain, the ratio of output voltage, current or power to input. (An amplifier is a circuit that has a power gain greater than 1.)

“The message, is that the easy answer isn’t always right.”Dr. Michael Prairie, Norwich University electrical engineering professor

Electronics II, which continues lessons from Electronics I, uses electronic engineering’s building blocks — diodes, bipolar and metal-oxide-semiconductor transistors and other components to control gain, frequency response, and other network functions. Students explore circuits of all sorts, including power circuits, sensor circuits and control circuits.

Prairie, the Electrical and Computer Engineering Department chairman, said Monday’s lab experiment aimed to have students control how much power gain is used to amplify the signal — from the guitar, for example — without letting things they can’t control affect it.

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Dr. Michael Prairie, a Norwich University electric engineering professor, explains an equation in his Electronics II lab on Monday. His students spent the period building circuits and testing power gain. (Photo by Mark Collier.)

Prairie wanted his students to ensure that heat didn’t influence their circuits’ stability. Using the guitarist analogy, it would be important that the amplifier’s performance was linked to just the strumming of strings rather than the streaming of the sun warming the amp on an outdoor stage. (He had the students warm some transistors in their hands to introduce temperature variability.)

Monday’s class used a voltage meter to gauge the stability of their circuits’ signal. Prairie said the students built some circuits that were very simple and delivered the immediate gratification of a good signal. Other circuits they built were a little more complicated, but the extra effort seemed to yield only the same results.

When heat was added, though, the simple circuit’s output changed a lot, while the more complicated circuit’s output was rock solid.

“The message,” he said, “is that the easy answer isn’t always right.”

Junior Tyler Horn, who hopes to remotely pilot aircraft in the U.S. Air Force and work in robotics afterward, said the lab exercise taught him to explore many options when problem solving.

“Sometimes the measurements we take are not always right due to many factors,” he said in an email, “and all answers should be tested.”

Musical connection

That Prairie, a 1983 Norwich graduate, would use a music analogy for engineering makes sense. As a Norwich undergraduate, Prairie played the baritone horn in the Regimental Band for a year before pursuing other Corps leadership opportunities.

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Electronics II students at Norwich University explore circuits of all sorts, including power circuits, sensor circuits and control circuits. (Photo by Mark Collier.)

In 2010, Prairie and Norwich mechanical engineering professor R. Danner Friend co-published “Machine Shop Training with a Musical Note,” a paper detailing a hands-on machine-shop training activity that created a useful object, in this case, a simple flute. 

Although civil engineers might imagine bridges rising and mechanical engineers might imagine gears turning, electrical engineers must see networks abstractly because electrical signals and gains are mostly invisible. (People who don’t study electrical engineering might see his class’s experiments as indecipherable clots of colored wire.)

Prairie said he sometimes imagines electrical networks like a plumber might imagine pipe networks — resistors of different sizes are like pipes of different diameters; flowing electricity replaces flowing water.

Part of Monday’s goal, Prairie said, was showing that the circuits in the textbooks look like perfectly built, perfectly performing circuits. Real-life circuit building, however, is trickier and messier.

“There’s a squishiness,” he said. “That’s a really unscientific term, but it describes how some of these things (like transistors) work if we’re not careful how we use them in the real world.”

Click here to see the full photo gallery from Monday.



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