Electrical Engineering Basics Quiz

Boolean Logic and ADC

• Includes AC power and Analog to Digital Conversion
• Ecor1044 is the course code

History of Invention

• Edison held over 1000 US patents

• First patent was for an electric vote recorder in 1869

• Major innovation was the establishment of an industrial research lab in 1876

• First successful light bulb in 1879, lasting 13.5 hours

• Edison developed the first commercially successful incandescent light bulbs in 1880

• Edison founded the Edison Illuminating Company to create electric power utilities

• Tesla, a Serbian-American, was known for AC power

• Joined Edison's company in 1884

• Left after 6 months due to a bonus dispute

• Invented the arc lighting system

• Secured investor funding and launched a competing utility company in 1886

• Created the induction motor that used alternating current in 1887

War of Currents

• Tesla licensed his AC patents in 1888
• DC power delivery systems faced competition from AC systems
• DC power was limited to one mile from the plant
• Transformer technology, developed between 1885-1886, enabled long-distance transmission of AC power over thinner wires and cheaper wire. The voltage could be reduced at the destination.

AC Sources

• AC sources are periodic (same amplitude)
• Angular frequency (ω) is defined as ω = 2πf
• Voltage (V(t)) is expressed as V(t) = V₀ sin ωt, where V₀ is the peak voltage, and ω is the angular frequency

Resistive Load

• For a resistive load, the phase angle (φ) is 0
• Voltage (V(t)) is expressed as V(t) =V₀ sin ωt
• Current (IR(t)) is expressed as I(t)= I₀ sin at

Inductive Load

• Current lags voltage by π/2 in a purely inductive circuit
• Voltage (V(t)) is written as V(t) = V₀ sin ωt
• Inductive current (IL(t)) is demonstrated as I(t)= I₀ sin(ωt – π/2)

Capacitive Load

• Current leads voltage by π/2 in a capacitive circuit
• Voltage (V(t)) is demonstrated by V(t)= V₀ sin ωt

Summary of Circuit Elements

• Resistive (R) element has a phase angle of 0
• Inductive (L) element has a phase angle of π/2
• Capacitive (C) element has a phase angle of -π/2

Power (Active, Reactive, Apparent)

• Active power (kW) powers and performs useful work.
• Reactive power (kVAR) is required to produce magnetic flux.
• Apparent power (kVA) is the vector summation of kW and kVAR.

Power Factor

• Power factor (PF) is calculated as PF = kW/kVA = cos θ
• PF should be close to 1

Analog vs Digital Signals

• Analog signals have an infinite number of increments
• Digital signals have finite number of values

Analog to Digital Converter (ADC)

• ADC converts continuous analog signals to discrete digital values.
• ADCs are used in microcontrollers, computers, and systems that use real-world data like temperature, voltage and pressure.
• The signal conversion is done by sampling the analog signal at regular intervals.
• Sampling values are quantized to finite sets of digital codes.

Key Parameters of ADCs

• Resolution: The number of bits used to represent the digital output.
• Sampling rate: How frequently the ADC samples the analog signal.
• Input range: The voltage range the ADC can measure from a minimum to a maximum.

Challenges of ADCs

• Noise sensitivity: ADCs are sensitive to noise, which degrades their accuracy. Proper shielding, filtering, and design minimize noise.
• Power Consumption: ADCs (high speed) use considerable amounts of power.
• Trade-off between speed and accuracy: High-precision ADCs may be slower and high-speed ADCs can have less precision. Designers need to choose the correct ADC type and configuration based on the application

Applications of ADCs

• Sensors: Convert analog sensor data into digital form for further processing
• Data acquisition systems: Systems gather and process data using analog information.
• Communication systems: Convert analog signals into digital form.
• Control Systems: Digitalize sensor data for control applications.

Audio and Music / Sensors

• Converting sound waves to digital form (e.g., MP3 encoding)
• Temperature, pressure, and light sensors convert analog signals for use in microcontrollers.

ADCs Working Principle

• Sampling: The continuous analog signal is sampled at discrete intervals (sample rate)
• Encoding/ Quantizing: The sampled signal is approximated to the nearest value within a defined range
• Key parameters: sampling rate / resolution

ADCs: Old vs. New Models

• Resolution: Old models typically had lower resolution (8-10 bit resolution). New models have higher resolution(12-24 bits).
• Conversion Speed: Old models were slower (kilo samples per second). Modern ADCs are much faster (megahertz, gigahertz).
• Power Consumption: Older ADCs are less power efficient using older transistor technology. New models are more power efficient due to improvements in semiconductor technology.

Choosing the Right ADC

• Resolution: How precise measurements need to be ?
• Sampling Rate: How fast the signal changes and how often sampling is needed
• Power Consumption: Important for battery powered systems
• Cost: Higher performance ADCs are typically more expensive

Resolutions of ADCs

• Graph showing error decreases as resolution increases.

Analog to Digital Converter (ADC)

• Uses a sample and hold system that takes an analog signal, converts it using a A/D converter to an equally spaced digital format

What does the ADC do?

• Converts analog signals into binary words
• Binary words can have different lengths. Higher the number of bits, higher the resolution.

Analog to Digital Conversion - 3 Steps

• Sampling: Continuous to Discrete time
• Quantizing: Discrete time to discrete Amplitude
• Encoding: Discrete amplitude to binary

Analog to Digital Conversion (Experiment 1)

• Convert a time-varying analog signal from 0 to 7 volts into a digital signal using a three-bit ADC.

Quantization Details

• Resolution/Quantization step size (Q): Represents the smallest voltage that can be encoded digitally by the least significant bit.

Quantization Details (experiment 2)

• Given a 0-10V analog signal, how to separate the voltages into 3-bit binary words?
• Quantize each interval, calculate step size and binary equivalents.

Accuracy of A/D Conversion

• Increasing resolution and sampling rate improve accuracy.

Converting a Voltage to Binary (Experiments 4 and 5)

• For a range of 0-5V / -5V to 5V and 10bit resolution; determine respective binary values.

Sampling Rate or Frequency

• Sampling rate is the frequency at which an ADC samples an analog signal. A higher sampling rate typically results in higher accuracy.

Limitation: Aliasing

• Causes different signals to become indistinguishable during sampling.
• Occurs when the input signal changes faster than the sample rate.
• Nyquist rule: Using a sampling rate at least twice as the highest frequency helps avoid aliasing.

Logic Gates

• Uses Complementary Metal-Oxide-Semiconductor (CMOS) transistors.

Identification of Integrated Circuits (ICs)

• Integrated circuits (ICs) include AND, OR, and NOT gates, represented by 7408 (AND), 7432 (OR), and 7404 (NOT), respectively. Pin numbers are relevant for identifying ICs by their function

Integrated Circuits (ICs) (Page 44)

• Circuits are used to implement different combinational logic circuits
• Use Transistor-Transistor Logic (TTL) family.