Understanding Modern Electronics

Meet the battery! This lecture marks your introduction to circuit diagrams, displaying the interconnected assemblages of electronic components that make a circuit function. Learn how to decipher these drawings, and see how components assembled in series or in parallel may interact differently depending on their configuration.

As you grow familiar with physical properties of electric circuits, become acquainted with the instruments used to measure these quantities: voltmeters, ammeters, ohmmeters, multimeters, and the oscilloscope. See how each of these instruments interacts with a circuit to test circuit behavior or measure quantities that may vary over time.

Examine the nuances of alternating and direct currents, see how transformers use electromagnetic induction to transform voltage levels in AC circuits, and observe the role of diodes and capacitors in regulating current. See how the DC power supplies that charge our cell phones are constructed so that they convert alternating to direct current.

From familiar audio equalizers we use to crank the bass or reduce hiss, to cell phone towers that need to separate calls coming in on adjacent channels, filtering electronic signals is often essential. Dive further into the critical role that capacitors play in electronic filters.

Semiconductors make possible the transistors at the heart of electronics, including integrated circuits and computers. Learn how the atomic configuration of semiconductors makes them unique, and how engineers adjust their properties to make two types of semiconductors - P and N. Witness the critical role that PN-junctions play in semiconductor devices.

Transistors in all forms fundamentally do the same thing: they allow one electronic circuit to control another. Review the concept of electronic control, and study field effect transistors (FETs) as well as bipolar junction transistors (BJTs). See how the bipolar junction transistor can be used as a simple switch.

Discover how transistors can be used to increase voltage, current, or power of an electronic signal while faithfully reproducing the signal's time variation. See how biasing and load-line analysis play key roles in amplifiers, and help prevent distortion. Learn to design a simple one-transistor audio amplifier that increases the voltage of audio-frequency signals.

Put your knowledge to use by building a complete audio amplifier. First, create a two-stage amplifier, then add capacitors to increase the amplification, or gain. Add a power output stage to drive a loudspeaker. Finally, add a volume control. In addition, learn how biasing with diodes can eliminate a subtle form of distortion.

Learn why large gain - infinite gain, in fact - as well as low output resistance and high input resistance are characteristics of the ideal amplifier. See how an integrated-circuit operational amplifier, or "op-amp," puts all these things together and also how the op-amp can be used as a simple comparator.