An Introduction to Electronic Circuit PDF

An Introduction to Electronic Circuit Charito B. Taguba, PhD Instructor Learning Objectives At the end of the session, you will be able to: define and understand digital logic and electronic circuits; analyze the components and parameters of circuit; an...

An Introduction to Electronic Circuit Charito B. Taguba, PhD Instructor Learning Objectives At the end of the session, you will be able to: define and understand digital logic and electronic circuits; analyze the components and parameters of circuit; and differentiate the advantages and disadvantages of analog and digital signal. What is an Electric Circuit? In the simplest terms, an electric circuit is a pathway for an electric current to flow from one point to another. From a high level, every circuit has three basic components: Voltage source Conductive path A Load Sample Electric Circuit  Voltage Source A voltage source introduces energy into a circuit via a potential difference between its positive (+) and negative (–) terminals. Voltage sources can be Alternating Current (AC) or Direct Current (DC) – the main difference being how the current flows. AC sources produce voltages that vary sinusoidally, i.e. the current reverses direction periodically. Examples are power from the grid or generators. On the other hand, DC sources produce current that flows in one direction. Batteries are a source of DC voltage.  Conductive Path A conductive path (aka a conductor) provides a medium for current flow through a circuit. These components have a very low resistance to current, e.g., copper wires, lead solder, or metallic traces on a printed circuit board (PCB). Conductors also help link other components together to achieve a single function. Load A load is any device that consumes power in a circuit. It can be anything from a light- emitting diode (LED) to a motor or siren. During a short circuit, the load is the conductor itself which generates heat, dissipating electric power.  3 Types of Loads Resistive Loads Loads consisting of any heating element are classified as resistive loads. These include incandescent lights, toasters, ovens, space heaters and coffee makers.  Inductive Loads Loads that power electrical motors are inductive loads. These are found in a variety of household items and devices with moving parts, including fans, vacuum cleaners, dishwashers, washing machines and the compressors in refrigerators and air conditioners.  Capacitive Loads In a capacitive load, current and voltage are out of phase as with an inductive load. The difference is that in the case of a capacitive load, the current reaches its maximum value before the voltage does. The current waveform leads the voltage waveform, but in an inductive load, the current waveform lags it. Electric Circuit Analysis: Types of Components An electronic component is an element within an electronic circuit that affects the flow of current or electromagnetic fields. Many modern circuits comprise passive, active, and electromechanical components.  Passive components Passive components are elements that consume electric power without introducing any net energy into a circuit. Common examples are resistors, capacitors, and inductors.  Active components Active components control the flow of current in electric circuits. These elements may amplify current, inject it into a circuit, or produce a power gain. Transistors, thyristors, and triode vacuum tubes are all active components.  Electromechanical components Electromechanical components are components that utilize electric current or voltage in a circuit to perform a mechanical function, e.g., DC motors or relays. In the case of electromechanical solenoids, voltage is used to actuate a set of mechanical contacts by varying the inductance in its coil. Electronic components on a breadboard. Image credit: Pixabay.  Relay A relay is an electrically operated switch. A current is passed through a mechanical coil on one side of the relay which causes switch contacts to move on the other side. There is no electrical connection between the input and output, so a relay is often used to switch electrical circuits involving higher voltages than the input signal.  A reed relay is a relay that uses a reed switch instead of a mechanical arm operated switch. These are only suitable for switching small loads, but can often be driven directly from a smaller signal such as the output from an Arduino or from the PiFace digital.  An electrical motor uses an electrical current to induce a magnetic field that causes it to rotate. A standard DC motor is driven using a direct current. If the direction of the current is reversed then the direction of rotation will also be reversed. Electric Circuit Analysis: Circuit Parameters Current and voltage are the most essential parameters of electric circuits. Similarly, resistance, inductance, and capacitance are vital attributes of electronic components.  Current Electric current is the flow of electrons through a circuit. The unit of measurement for current is Ampere (A). As we discussed earlier, the current can be AC or DC. We can find the value of current flowing through a circuit using Ohm’s law which states that the current between any two points is proportional to the potential difference between them. The equation is I = V/R (Where I is current, V is voltage, and R is resistance). Practically, we can obtain the value of current in a circuit using a digital multimeter.  Voltage Voltage (V) sometimes referred to as Electromotive force (E) is the potential difference between any two points in an electric circuit. The unit of measurement is the Volt. Like a current, the voltage can be AC or DC. Voltage can also be derived from Ohm’s Law using the formula V = IR (Where V is voltage, I is current, and R is resistance). Passive components. Image Credit: Pixabay Resistance Resistance is the attribute of a component to resist the flow of electric current through a circuit. The unit of measurement is Ohms (Greek symbol: Ω).  According to Ohm’s Law, the resistance of a conductor is the ratio of voltage (V) flowing across it to the current (I) flowing through it. Mathematically, R = V/I (Where R is resistance, V is voltage, and I is current). Every component (except superconductors) offers varying levels of resistance. However, resistors are designed especially for that purpose. They are two-terminal, passive components having varying resistances. Some resistor types are marked with color codes to indicate the resistances and tolerance they offer. Inductance Inductance is the tendency for a magnetic field to be induced in a conductor when an electric current flows through it. The strength of this induced magnetic field is proportional to the magnitude of the current. The unit of measurement for inductance is Henrys (H), named after Joseph Henry, the American scientist that discovered it.  Inductors Inductors, aka chokes or coils, are simple passive components that can store up energy in magnetic form when electric current flows through them. They consist of a conductor wound into a coil which generates a magnetic field in the opposite direction when an electric current is applied. We can calculate the inductance in an electric circuit using the formula: L = V/(di/dt) (Where L is the inductance, V is the potential difference across the coil, and di/dt is the rate of change of current in A/s).  Capacitance Capacitance is the ability of a circuit element to store an electric charge when a potential difference exists between its terminals. The unit of capacitance is the Farad, named after Michael Faraday, the scientist that discovered electromagnetic induction. To determine the capacitance of a component in an electric circuit, we can use the formula: C = Q/V (Where C is the capacitance in coulombs, Q is the charge, and V is the potential difference).  Signal Signal can be defined as a physical quantity, which contains some information. It is a function of one or more than one independent variables. Signals are of two types. Analog Signal Digital Signal  Analog Signal An analog signal is defined as the signal having continuous values. Analog signal can have infinite number of different values. In real world scenario, most of the things observed in nature are analog. Examples of the analog signals are following. Temperature Pressure Distance Sound Voltage Current Power Graphical representation of Analog Signal (Temperature)  Analog Circuits or System The circuits that process the analog signals are called as analog circuits or system. Examples of the analog system are following. Filter Amplifiers Television receiver motor speed controller DISADVANTAGE OF THE ANALOG SYSTEMS Less accuracy Less versatility More noise effect More distortion More effect of weather  Digital Signal A digital signal is defined as the signal which has only a finite number of distinct values. Digital signal are not continuous signal. In the digital electronic calculator, the input is given with the help of switches. This input is converted into electrical signal which having two discrete values or levels. One of these may be called low level and another is called high level. The signal will always be one of the two levels. This type of signal is called digital signal. Examples of the digital signal are following. Binary Signal Octal Signal Hexadecimal Sign Graphical representation of the Digital Signal (Binary)  Digital Systems or Digital Circuits The circuits that process that digital signal are called digital systems or digital circuits. Examples of the digital systems are following. Registers Flip-flop Counters Microprocessors  ADVANTAGE OF DIGITAL SYSTEMS More accuracy More versatility Less distortion Easy communicate Possible storage of information Comparison of Analog and Digital Signal S.N. Analog Signal Digital Signal 1 Analog signal has a infinite values. Digital signal has a finite number of the values. 2 Analog signal has a continuous nature. Digital signal has a discrete nature. Analog signal is generate by transducers and signal 3 Digital signal is generate by A to D converter. generators. 4 Example of analog signal: sine wave, triangular waves. Example of digital signal: binary signal. Mabbalo!!!