Electronics and Power Systems Lecture Review

Vocabulary practice flashcards covering power electronics, amplification stages, operational amplifiers, and digital logic circuits based on the lecture transcript.

SMPS

Switch Mode Power Supply; a regulating circuit where the transistor is switched on/off, making it more efficient, lighter, and smaller than linear versions.

Chopper

A transistor fed by DC from a rectifier and driven by a pulse source with continuous pulses.

Voltage Doubler

A circuit composed of two separate half-wave rectifiers and reservoir capacitors that provides a DC output equal to double the peak value ($pk-pk$) of the input voltage.

Simple Shunt Regulator

A circuit where a transistor acts as a variable resistance in parallel with the load ($R_L$) to maintain constant output voltage.

Zener Diode ($D_1$)

A component used in regulator circuits to provide a constant reference voltage, such as $5.6\,V$ at the base of a transistor.

Series Regulator

A regulator circuit where the transistor provides an increased load current to maintain a steady output voltage when the load current reduces.

Input Coupling Capacitor ($C_1$)

Prevents DC from the preceding stage from affecting the DC bias set by the potential divider in an amplifier.

Potential Divider ($R_2$, $R_4$)

A resistor network providing the forward bias for a transistor to ensure it remains in the "on" state, often with a ratio of approximately $9:1$.

Emitter Bias ($R_3$)

Raises the emitter and base voltages to ensure the transistor is biased in the linear portion of its $V_{BE}$ or $I_C$ characteristics.

Collector Load Resistor ($R_{10}$)

Provides an output voltage proportional to the collector currents.

Output Signal Coupling Capacitor ($C_2$)

Prevents DC from the collector from affecting the next stage of the amplifier circuit.

Class B Amplifier

An amplifier using two or more transistors biased to conduct only one half of the input waveform each, doubling efficiency to approximately $70\%$.

Crossover Distortion

Distortion in amplifiers caused by transistors needing approximately $0.7\,V$ to switch on, resulting in inaccurate reproduction of the waveform below that threshold.

Diac ($D_1$)

A component that acts like a zener diode, only allowing current to flow in one direction until it reaches a specific value.

Triac ($D_2$)

A device similar to a silicon rectifier that allows current to flow in both ways if there is current through the gate.

Op-amp Integrator

A circuit where feedback occurs via a capacitor rather than a standard resistor, used to convert square waves to triangular waves.

Virtual Earth

A point in an op-amp circuit that is not connected directly to earth but maintains the same potential ($0\,V$) due to the high input impedance and properties of an ideal op-amp.

Ideal Op-amp Properties

Characteristic traits including infinitely high open-loop voltage gain, infinitely high input impedance, zero output impedance, and zero drift.

Wien Bridge Oscillator

A type of oscillator that generates sine waves across a large range of frequencies using resistors and capacitors with the formula $f = \frac{1}{2\pi RC}$.

Monostable Pulse Circuit

A circuit that produces a single pulse with a duration calculated by $1.1 \times C \times R$ seconds.

Mod 10 Counter

An asynchronous ripple counter that counts from $0$ to $9$ ($0000$ to $1001$ in binary) and resets on the 10th clock pulse.

Multivibrator

A two-stage switching circuit where the output of one stage feeds the input of the other, often forming square waves.

Bistable

A circuit that is stable in either of two states (Set or Reset) and does not change until it receives an appropriate signal.

Indeterminate State

An undesirable condition in an SR bistable where $S=0$ and $R=0$, leading to unpredictable behavior.

Debouncing

The use of an anti-bounce circuit (SR bistable) to clean up extra electrical pulses caused by the rapid bouncing of mechanical switch contacts.

Switched-Mode Power Supply (SMPS)

Regulates output voltage by using a chopper transistor driven by a pulse source providing continuous pulses; DC from the rectifier feeds the chopper, powering the load with energy stored in an inductor when the transistor is off. Feedback monitors output voltage and adjusts pulse frequency for regulation, resulting in smaller components, higher efficiency, and lighter weight.

Voltage Doubler Circuit

Produces double the peak input voltage by utilizing two half-wave rectifiers to charge two capacitors; during the first half-cycle, D1 charges C1 to peak voltage, and in the second half-cycle, D2 charges C2 to the same peak voltage, leading to an output voltage of C1 + C2.

Shunt Regulator

Maintains constant output voltage using a Zener diode that provides a fixed reference voltage, while a transistor acts as variable resistance; it adjusts conduction based on load current and input voltage variations.

Series Regulator

Maintains output voltage with a Zener diode fixing the base voltage of a transistor; if the load current decreases, the voltage across the load increases, causing the transistor to conduct more, thereby stabilizing the output.

Common-Emitter (CE) Amplifier Components

C1 is an input coupling capacitor blocking DC; R2 and R4 form a potential divider providing forward bias; R3 is the emitter bias stabilizing the transistor; R1 is the collector load resistor converting collector current to voltage; C2 is the output coupling capacitor that blocks DC to the next stage.

Class-B Amplifier

Operates using two complementary transistors, each conducting one half of the waveform; achieves approximately 70% efficiency but can have crossover distortion due to the transistor conduction threshold.

TRIAC/DIAC Power Control Circuit

Functions with a DIAC conducting after hitting breakover voltage to trigger the TRIAC, which conducts in both directions when gate current is applied; R1 controls the charge rate influencing firing angle and output.

Op-Amp Integrator

Works by using a capacitor in the feedback path, producing an output that is the integral of the input signal; the virtual earth concept keeps the inverting input at 0 V, and a reset switch can discharge the capacitor.

Ideal Op-Amp Properties

Defined by infinite gain, infinite input impedance, zero output impedance, and zero drift.

Positive vs. Negative Feedback

Positive feedback increases output leading to potential instability, while negative feedback stabilizes gain and reduces distortion providing a predictable output.

Definitions in Op-Amps

Input bias current is the average of input currents; offset voltage is the output error when inputs are equal; offset current is the difference between input currents; CMRR is the ability to reject common-mode noise; slew rate is the maximum rate of output voltage change.

Wien Bridge Oscillator

Generates sine waves using an RC network, with frequency given by the formula ( f = \frac{1}{2\pi RC} ); requires a minimum gain of 3 and phase shift of 0° or 360°.

555 Timer Monostable Pulse Circuit

Initializes a timing cycle with a trigger pulse; the output remains HIGH for a duration calculated by ( T = 1.1 \times R \times C ) and returns to LOW once the capacitor reaches threshold.

Mod-10 Ripple Counter

Asynchronous counter that counts from 0000 to 1001 using four flip-flops; the count resets after detecting 1010 with an AND gate, activating the active-low CLR.

States of an SR NAND Latch

Set state (S=0, R=1) leads to Q=1 and Q̅=0; reset state (S=1, R=0) leads to Q=0 and Q̅=1; latched state (S=1, R=1) holds the previous state; indeterminate state (S=0, R=0) results in Q=1 and Q̅=1, indicating an invalid state.

Bistable Switch Bounce Removal

Eliminates switch bounce by latching the output state to ignore multiple transitions caused by mechanical switches.

Manchester Encoding

Splits each bit into halves where Logic 0 is represented by a low-to-high transition and Logic 1 by a high-to-low transition; it is a self-clocking method that reduces synchronization errors.

Grey Code Usage

Used instead of binary because only one bit changes at a time, preventing false readings in mechanical sensors and reducing error magnitude.

Multiplexer and Demultiplexer

A multiplexer combines multiple signals into one line, while a demultiplexer separates that signal back into multiple outputs; time-division multiplexing allocates time slots for each input.

Noise Margins (NMH and NML)

Defined as NMH = VOH(min) – VIH(min) and NML = VIL(max) – VOL(max), these margins indicate the tolerance to noise before errors occur.

Half-Split Fault-Finding Method

Involves dividing the circuit into halves and testing the midpoint to isolate faults, focusing on the earlier or later half as needed.

Digital Circuit Testing Tools

Includes Digital Multimeter for measuring voltage and continuity, Oscilloscope for observing waveforms, Logic Probe for assessing logic levels, and Signal Generator for injecting test signals.