Name: circuit source symbols and controls
Uploaded: 2024-04-11T12:48:28.000Z
Duration: 1 min 18 s
Channel: JoVE

מקורות במעגל יכולים להיות עצמאיים או תלויים.
מקורות מתח או זרם עצמאיים מספקים מתח וזרם שאינם מושפעים מרכיבי מעגל אחרים.
לסמלים של מקורות מתח עצמאיים יש קטבים, בעוד שמקורות זרם עצמאיים משתמשים בחצים כדי לציין את כיוון הזרם.
קצר חשמלי הוא מקור מתח בלתי תלוי במתח אפס, בעוד שמעגל פתוח הוא מקור זרם בלתי תלוי בזרם אפס.
מקורות תלויים הם מחוללי מתח או זרם הנשלטים על ידי רכיבי מעגל אחרים. הם מיוצגים על ידי צורת יהלום.
בהתבסס על החלקים השולטים והמבוקרים שלהם, מקורות תלויים מחולקים לארבע קטגוריות.
חשבו על מעגל שבו המתח של המקור התלוי נשלט על ידי הזרם דרך הנגד.
אם מוסיפים קצר חשמלי בסדרה עם הנגד, הזרם השולט שווה לזרם בקצר.
מתח המקור ליחס הזרם השולט מייצג את הרווח של המקור התלוי.
באופן דומה, מתח השליטה יכול להיחשב כמתח במעגל פתוח.
לכן, המתח או הזרם של המקורות התלויים פרופורציונליים למתח או לזרם השולט.

מקורות עצמאיותלויים

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	במעגלים חשמליים, למקורות יש תפקיד מכריע באספקת חשמל לתפעול המעגל. ניתן לסווג מקורות אלו בגדול לשני סוגים: עצמאי ותלוי. 

	מקורות מתח או זרם עצמאימספקים כמות קבועה של מתח או זרם, בהתאמה, שאינה מושפעת מאלמנטים אחרים במעגל. אלה מיוצגים באמצעות סמלים ספציפיים. מקורות מתח עצמאימסומלים בקוטביות (+ ו-), המציינים את כיוון הפרש הפוטנציאלים, בעוד שמקורות זרם עצמאימשתמשים בחצים כדי לציין את כיוון זרימת הזרם. 

	היבט מעניין של מקורות עצמאיהוא שקצר חשמלי יכול להיחשב כמקור מתח עצמאי במתח אפס מכיוון שהוא מאפשר לזרם לזרום בחופשיות ללא נפילת מתח. לעומת זאת, ניתן לחשוב על מעגל פתוח כמקור זרם עצמאי בזרם אפס, בהתחשב בכך שהוא מונע כל זרימת זרם ללא קשר למתח המופעל. 

	מצד שני, מקורות תלויים הם מחוללי מתח או זרם שהערכים שלהם נשלטים על ידי אלמנטים אחרים באותו מעגל. הם מתוארים על ידי צורת יהלום בדיאגרמות מעגלים. 

	מקורות תלויים אלה מחולקים עוד יותר לארבע קטגוריות בהתבסס על החלקים השולטים והמבוקרים שלהם: מקורות מתח מבוקרי מתח (VCVS), מקורות מתח מבוקרים זרם (CCVS), מקורות זרם מבוקרי מתח (VCCS) ומקורות זרם מבוקרים. (CCCS). 

	לדוגמה, במעגל שבו פלט המתח של מקור תלוי נשלט על ידי הזרם הזורם דרך נגד, אם מתווסף קצר חשמלי בסדרה עם הנגד הזה, זרם השליטה הופך שווה ערך לזרם בקצר. היחס בין מתח המקור לזרם השולט מייצג את הרווח של המקור התלוי. 

	באופן דומה, מתח השליטה יכול להיחשב כמתח במעגל פתוח. המשמעות היא שהמתח או הזרם של המקורות התלויים הם פרופורציונליים למתח או הזרם השולט.

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מקורות במעגל יכולים להיות עצמאיים או תלויים.
מתח עצמאי או מקורות זרם מספקים מתח וזרם שאינם מושפעים ממעגל אחר ...

Education

JoVE Core

Electrical Engineering

הנדסה חשמלית

Unit 1

יחידה 1

Basics of Electric Circuits

יסודות מעגלים חשמליים

KEY TERMS AND CONCEPTS

מונחים ומושגים מרכזיים

Independent and Dependent Sources

circuit source symbols and controls

Circuit sources in electrical circuits can be independent or dependent. They provide the power a circuit needs to operate. Independent voltage sources supply a fixed voltage, and independent current sources supply a fixed current. Their output does not change because of other parts in the circuit.

These sources use standard symbols in circuit diagrams. An independent voltage source is shown with + and - signs to mark the potential difference. An independent current source is shown with an arrow to show the direction of current flow. A short circuit can be treated as a zero-voltage independent voltage source because it allows current to flow with no voltage drop. An open circuit can be treated as a zero-current independent current source because it blocks current flow even when voltage is applied.

Dependent sources work differently. Their voltage or current is controlled by another element in the same circuit. They are drawn with a diamond shape. There are four types: voltage-controlled voltage sources, current-controlled voltage sources, voltage-controlled current sources, and current-controlled current sources.

The controlling part can be tied to a resistor or another circuit element. For example, if the output voltage of a dependent source is controlled by the current through a resistor, adding a short circuit in series with that resistor makes the controlling current the same as the current in the short circuit. The ratio of the source voltage to the controlling current gives the gain of the dependent source. In a similar way, the controlling voltage can be treated as an open-circuit voltage. This means the voltage or current from a dependent source is proportional to the controlling voltage or current.

Circuit Source Symbols and Controls

charge and current

Electric Charge in Circuits

Electric charge in circuits explains how charged particles behave in matter and how current is produced. Everyday static effects, like a wool sweater sticking to the body or a shock from a carpet, show charge in action. Charge is an inherent property of atomic particles and is measured in coulombs (C). Matter is made of atoms with electrons, protons, and neutrons. Electrons carry a negative charge (-e), and protons carry a positive charge (+e). These two charges have the same magnitude. An...

voltage

Voltage in Electric Circuits

Voltage in electric circuits is the energy needed to move electric charge between two points. It is also called electromotive force, or EMF. In most circuits, an external force such as a battery provides this energy for electron movement in a conductor. The voltage between points a and b is written as v_ab. It is defined as the work, or energy, needed to move a unit charge from point a to point b. In the equation, w is the energy in joules and q is the charge in coulombs. Voltage is measured...

power and energy

Circuit Power, Absorption, and Supply

Circuit power, absorption, and supply explain how much energy an element uses or delivers in an electric circuit. These ideas matter in electrical engineering because power and energy calculations help describe circuit behavior. A 100-watt light bulb, for example, emits more light than a 60-watt bulb, so wattage is a useful measure in real devices. Power is the time rate of expending or absorbing energy. It is measured in watts, written as W. The relation between power and energy uses the...

electric circuit elements

Circuit Elements: Passive, Active, and Linear

Circuit elements are the building blocks of an electric circuit. An electric circuit is the connection of these elements. In this context, circuit elements are often grouped by how they behave and whether they supply energy. One major group is passive elements. These elements do not generate energy. Common passive elements include resistors, capacitors, and inductors. The other group is active elements, which can generate energy. Generators, batteries, and operational amplifiers are typical...

circuit terminology

Circuit Parts: Branches, Nodes, and Loops

Circuit parts like branches, nodes, loops, and meshes help describe how electrical networks work. An electrical network is a system of connected elements, such as resistors, capacitors, inductors, and voltage or current sources. Unlike a circuit, a network does not have to form a closed path. A circuit is also made of connected electrical elements, but it must include one or more closed paths. These loops let current flow continuously, which is what makes the circuit operate. Because of this,...

independent and dependent sources

Circuit sources in electrical circuits can be independent or dependent. They provide the power a circuit needs to operate. Independent voltage sources supply a fixed voltage, and independent current sources supply a fixed current. Their output does not change because of other parts in the circuit. These sources use standard symbols in circuit diagrams. An independent voltage source is shown with + and - signs to mark the potential difference. An independent current source is shown with an...

ohm's law

Resistance and Conductance in Circuits

Resistance and conductance help explain how electric current moves through a circuit. Resistors are basic circuit parts made from metallic alloys or carbon compounds. They are used to model how a material resists current and to control and regulate electrical power in a circuit. Ohm's law describes the link between voltage and current across a resistor. The voltage across a resistor is directly proportional to the current through it. The constant that sets this relationship is resistance.

kirchhoff's current law

Kirchhoff's Current Law at Circuit Nodes

Kirchhoff's Current Law explains how current behaves at a circuit node. A node is the point where two or more circuit elements meet. The law says the current entering a node equals the current leaving it. That balance follows the rule of charge conservation, which means electric charge is not lost at the junction. When applying KCL, currents entering the node are treated as positive and currents leaving the node are treated as negative. The currents can be added algebraically at the node, and...

kirchhoff's voltage law

Voltage Balance in Closed Circuit Loops

Kirchhoff's Voltage Law explains how voltage is balanced in a closed circuit loop. It is a basic rule in electrical engineering and comes from the idea of energy conservation. Energy can change form, but it cannot be created or destroyed. KVL states that the algebraic sum of all voltages around a closed path, or loop, is zero. In other words, the total voltage supplied in a loop equals the total voltage drop across the components in that loop. A loop can be traced clockwise or anticlockwise,...

voltage dividers

Series Resistors and Voltage Split

Series resistors split voltage across a circuit. In a series setup, resistors are linked one after another. The same current flows through each resistor in the chain. To analyze this behavior, Ohm's law is used to relate voltage, current, and resistance. Kirchhoff's voltage law says the voltages around a series loop add up to the source voltage. That means the current in the circuit equals the source voltage divided by the total resistance in series. The current value can then be used in Ohm's...

current dividers

Parallel Resistors and Current Division

Parallel resistors share the same two nodes, so each resistor has the same voltage across it. In this circuit setup, Kirchhoff's current law applies. The source current equals the sum of the currents through each branch. Ohm's law helps find the branch currents from the source voltage and the resistor values. The source current is equal to the source voltage times the sum of the reciprocals of the resistances. This makes it easier to calculate how current divides in the circuit. The current...

equivalent resistance

Delta-Wye Network Conversion

Delta-wye network conversion helps analyze resistor circuits that are not arranged in simple series or parallel paths. These three-terminal equivalent networks use the wye (Y), also called tee (T), and the delta (Δ), also called pi (π), as practical circuit models. These networks are useful in many circuit settings. They appear in three-phase electrical systems, electrical filters, and matching networks. They can also be used on their own or combined with more complex circuits. A delta...

design example: resistive touchscreen

Resistive Touchscreen Voltage Mapping

A resistive touchscreen uses voltage mapping to locate a finger touch on a mobile device. It is built from two metallic layers. The top layer is flexible, and the bottom layer is rigid. A narrow gap separates them, and the high resistance between the layers is an important part of the design. When a user touches the screen, the two layers meet at one point. That contact point is called the touchpoint. The touch lowers the resistance between the layers at that spot and changes the electrical...

key terms and concepts

Learn how independent and dependent sources work in circuits, how they are drawn, and how control by voltage or current determines dependent source gain.

Circuit Source Symbols and Controls | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Circuit Source Symbols and Controls

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