Signal Processing: Filters
A filter circuit is a tool that helps clean up electrical signals. Just like a filter on a fish tank helps clean the water by catching dirt and debris, an electrical filter helps clean up electrical signals by catching unwanted parts of the signal. For example, imagine you are listening to a song on the radio, but there is a lot of static in the background. A filter can help clean up the sound by blocking out the static noise, so you can hear the music more clearly.
A low-pass filter allows low frequency signals to pass through, but attenuates high frequency signals (any signal above the designated cutoff frequency) more rapidly the higher the signal frequency. A high-pass filter works in the opposite way. It allows high frequencies to pass through, but blocks low frequencies, while a bandpass filter allows only frequencies between a certain range to pass, and a band-reject filter blocks signals of a certain range from passing.
Below, I designed a 3-stage RC low-pass filter with a cutoff frequency of 58 Hz. The Frequency Analysis graphs is a Bode plot, which depicts the signal attenuation for each stage in decibels.
Internet of Things: A Scene From The Future
The Internet of Things (IoT) is a network of interconnected devices, sensors, and software that work together to collect and exchange data. The impact of IoT is significant, as it is revolutionizing various industries, including healthcare, transportation, and agriculture.
Of the many industries impacted by IoT, healthcare has some of the most consumer noticeable applications. IoT enables remote patient monitoring, real-time patient data tracking, and more accurate diagnosis and treatment. Transportation is also greatly impacted by IoT. It improves the efficiency and safety of transportation systems by enabling real-time traffic monitoring, autonomous vehicles, and smart traffic management systems. Finally, IoT is also industrializing the agriculture industry. IoT enables precision farming by collecting, monitoring, and analyzing soil moisture, temperature, and nutrient levels in real-time, and provides predictive analytics.
IoT is revolutionizing many industries, and electrical engineers play a crucial role in developing and implementing IoT solutions. They are involved in designing sensors, embedded systems, networking infrastructure, and cloud computing solutions. As IoT continues to evolve, electrical engineers will continue to play a vital role in shaping the future of this field.
Matrix Laboratory, more commonly known as Matlab, is a powerful, high-level programming language and integrated development environment (IDE) that can handle complex mathematical equations and efficiently manipulate matrices and vectors. Since its introduction in the 1980s, it has revolutionized how engineers approach circuit analysis, design, and simulation due to its ability to navigate complex mathematical operations and interface with other hardware and software tools like Simulink. It can also generate plots to aid in analyzing and visualizing circuit responses to different input signals.
Matlab is particularly effective at time domain and frequency domain circuit analysis. For example, transforming a function from the frequency domain back into the time domain requires an inverse Laplace transform. The inverse Laplace transform can be tedious, time consuming, and prone to mistakes when solving by hand, especially when working with complex functions requiring techniques like partial fraction decomposition.
Matlab, on the other hand, can almost instantly calculate the inverse Laplace transform and plot the function. Matlab’s proficiency with the Laplace transform provides the mathematical framework for solving differential equations, deriving transfer functions, analyzing frequency response, and performing time-domain analysis. Its ease of dealing with the Laplace transform makes it an essential tool for analyzing circuits, streamlining the design process, and improving circuit performance.
CMOS (Complementary Metal-Oxide-Semiconductor) logic is a type of digital circuit design that uses pairs of MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) to implement logic gates. Due to their low power consumption and high noise immunity, CMOS logic circuits are commonly used in microprocessors, microcontrollers, and other digital systems.
CMOS logic has largely replace DTL (Diode-Transistor Logic) and TTL (Transistor-Transistor Logic) in most digital applications. Compared to DTL and TTL, CMOS logic has lower power consumption because CMOS gates only draw current when switching states, unlike DTL and TTL gates that draw current continuously. CMOS circuits are also less susceptible to noise because they use differential signaling, which cancels out common-mode noise. Another advantage of CMOS circuits is their high input impedance. The high input impedance prevents loading the previous stage of the circuit, allowing for many stages without causing significant signal degradation.
However, CMOS logic has some disadvantages compared to DTL and TTL logic. For example, there is a higher propagation delay, meaning it takes longer for a signal to move through a CMOS circuit. CMOS gates are also typically larger than DTL and TTL gates making them more expensive to manufacture.
Overall, CMOS’s wide operating range, high input impedance, high noise immunity, and low power consumption makes it the industry standard for most digital applications.
Diode-Transistor Logic and Transistor-Transistor Logic
Diode-Transistor Logic (DTL) and Transistor-Transistor Logic (TTL) are two popular families of digital logic circuits commonly used in the past. Although they have been gradually replaced by Complementary Metal-Oxide-Semiconductor (CMOS) logic circuits, DTL and TTL circuits are still used in specialized applications that require low-power or high -speed circuits.
Diode-Transistor Logic circuits utilize diodes and bipolar junction transistors (BJTs) to implement OR and AND operations. They consumer less power compared to other logic families, have a high noise immunity, and are simple to design. However, their slow switching speed and limited fan-out (number of gates connected to the circuit) limits its application in high-speed digital systems.
Transistor-Transistor Logic circuits utilizes only BJTs to perform AND and OR operations. They are simple to design, have a high fan-out allowing them to drive multiple loads, and can perform high-speed operations. Unfortunately, they consumer more power than other logic families, and are susceptible to interference.
Digital Logic Circuits
Digital logic circuits are circuits that operate on digital signals, which are discrete signals that take on a finite number of values, typically represented in binary. The circuits are composed logic gates, which are devices that perform logic operations on the input signals to produce an output signal. Common logic gates include AND, OR, NOT, NAND (Not AND), and NOR (Not OR).
All logic functions can be represented using a combination of AND, OR, and NOT gates, but it is more common that logic circuits utilize only NAND or only NOR gates as an equivalent representation of AND, OR, NOT combinations. NAND and NOR gates are commonly employed because any logic gate combination can be constructed using only NAND or NOR gates, and require fewer transistors than AND and OR gates to build, saving on cost and making it easier to manufacture. In some cases, NAND and NOR gates can also be faster than an AND, OR, NOT combination because of a shorter propagation delay. The cost-effectiveness, speed, and universality of NAND and NOR gates make them highly relevant in emerging digital technology.
Voltage Divider vs. Buck Converter
A voltage divider, which consists of two resistors in series, can be used to reduce or measure the voltage level of a signal. It is typically used in electronic circuits to bias transistors or set the gain of an amplifier.
Voltage dividers are nice because they only require two resistors and can be easily implemented in a circuit. However, it is not very efficient at reducing the voltage level because the output voltage may be affected by changes in the load resistance.
Buck converters, on the other hand, uses a switch, an inductor, and a diode to regulate the output voltage. The switch is turned on and off at a high frequency, causing the inductor to store energy when the switch is on and release it when the switch is off. The diode is used to prevent the inductor from discharging back into the input source.
A buck converter is a more efficient circuit at converting a higher voltage to a lower voltage due to its minimal power loss and the regulated output voltage not being affected by changes in the load resistance. Hoverer, it is more complex than a voltage divider and generates electromagnetic interference due tot he high-frequency switching, which can affect other components in the circuit.
Analog vs Digital Signals
An analog signal is a continuous signal that varies in time, taking on a range of values, including fractional values within its range. Analog signals are often used for applications that require continuous real-time measurements, such as temperature sensing, audio processing, and power monitoring. They are also used in control systems as they can regulate the output of a system based on input parameters. Thus, analog signals are used in microphones, voltage signals from a temperature sensor, or current signals from a motor.
A digital signal, on the other hand, is a discrete signal that has only two states: on or off, high or low, 1 or 0. Digital signals are a representation of analog signals that have been converted to binary code. Digital signals are easier to transmit, store, and process than analog signals because they are less subject to noise and other signal degradation. Digital signals are used for applications that require discrete, non-continuous signals, such as communication systems, computer processing, and digital audio and video. Digital signals are also used in signal processing, where they can filter, amplify, and manipulate digital data.
Both analog and digital signals have their unique advantages and disadvantages, so the choice of which signal to use depends on the specific application and the needs of the system.
Alternating Current (AC) vs Direct Current (DC) and the Feud Between Edison and Tesla
Direct current (DC) is an electrical current that flows in a single, continuous direction. Developed by Thomas Edison in the late 1870s, it is generated from batteries, solar cells, and fuel cells. The voltage in a DC circuit does not change. DC is commonly used in house hold appliances and for charging batteries or operating cellphones and laptops. However, there are some major limitations of DC. For example, it can only be transmitted over short distances before it requires a voltage boost, as it has excessive loss due to impedance from transmission lines.
In contrast, alternating current (AC), developed by Nikola Tesla in 1888, is a type of electrical current that changes direction periodically, typically several times per second. AC is more versatile than DC as it can be transmitted across long distances without significant loss, making it the preferred choice for power transmission in most countries. AC’s ability to be easily transformed into different voltages and frequencies also makes it a popular choice and is why it can be transmitted long distances. However, AC is more dangerous than DC because the rapidly changing magnetic field causes one’s muscles to contract, preventing a person from letting go of the wire, thus allowing it to cause significant damage to one’s organs and tissue. It is important to note, however, that DC shocks can also be fatal.
The feud between Thomas Edison and Nikola Tesla is one of the most famous and enduring rivalries in the history of science and technology. The intellectual battle between two brilliant inventors made pivotal contributions to the development of the electrical power system that we use today.
The feud was intense and personal, with each inventor using their influence with the media to promote their own views and discredit their rival. Edison went so far as to publicly demonstrate the dangers of AC by electrocuting stray dogs and a circus elephant named Topsy. Despite these efforts, AC power eventually became the dominant system for electrical power transmission, and Tesla’s contributions to the development of AC power were widely recognized. Despite their differences, both Edison and Tesla made important contributions to the development of electrical power and left a lasting legacy that continues to shape our world today.
Raspberry Pi in Electrical Engineering
The Raspberry Pi is single-board computer that was developed in the UK by the Raspberry Pi Foundation. It was designed as an affordable solution for teaching basic computer science in schools, and runs on an ARM architecture that supports a variety of operating systems, notably Raspberry Pi OS, a Linux-based distribution. As a small, compact computer, it is a popular tool for many projects due to its affordability and versatility.
Popular projects that incorporate the Raspberry Pi includes home automation, robotics, industrial control, data logging, and hobbyist retro gaming and media centers. For example, the Raspberry Pi can transform a home into a “smart home” by controlling or automating the lights, fans, and temperature when it is combined with software such as a Home Assistant or openHAB. With the help of these programs running on a Raspberry Pi, users can monitor their homes from anywhere in the world using their cellphone.
Raspberry Pie can also act as the “brain” of a robot, giving it the necessary processing power to control its movements and gather data. Its small size and affordability make it a popular choice for building robots for both education and industrial purposes.
Finally, Raspberry Pi is often utilized as a media center, as it allows users to stream music, movies, and even emulate classic video games on retro systems like Nintendo, Sega, and PlayStation. This enables users to enjoy their favorite old-school games on a single device.