Name: circuit source equivalents
Uploaded: 2025-05-22T09:06:14.000Z
Duration: 1 min 15 s
Channel: JoVE

La tecnica di trasformazione della sorgente consente la conversione di una sorgente di tensione in serie con un resistore in una sorgente di corrente equivalente in parallelo con il resistore o viceversa.
Durante la trasformazione, i valori del resistore nel circuito rimangono gli stessi. Utilizzando la legge di Ohm, è possibile determinare i valori di tensione o corrente.
La freccia della sorgente di corrente punta sempre verso il terminale positivo della sorgente di tensione.
Questa tecnica non può essere applicata a sorgenti di tensione e corrente ideali a causa delle loro caratteristiche di resistenza interna.
Si consideri un circuito costituito da una sorgente di tensione, una sorgente di corrente e alcuni resistori. Utilizzando la trasformazione della sorgente, è possibile determinare la caduta di tensione attraverso il resistore centrale.
Inizialmente, applicare la trasformazione dell'origine in entrambe le origini per ottenere il circuito ridotto.
Ora trasforma nuovamente la sorgente di tensione sinistra in una sorgente di corrente. Il circuito è ulteriormente semplificato in una configurazione a sorgente singola di corrente.
Utilizzando la formula della divisione di corrente, si ottiene la corrente attraverso il resistore. Sostituendolo nella legge di Ohm, si ottiene la caduta di tensione attraverso il resistore.

trasformazione della sorgente

La trasformazione della sorgente è una tecnica fondamentale impiegata nell'analisi dei circuiti, offrendo uno strumento prezioso per semplificare circuiti elettrici complessi. Questa tecnica prevede la sostituzione di una sorgente di tensione in serie con un resistore con una sorgente di corrente in parallelo con un resistore o viceversa. Il concetto chiave qui è che quando le sorgenti originali vengono disattivate (spente), la resistenza equivalente ai terminali terminali del circuito rimane la stessa.

È essenziale notare che quando si eseguono trasformazioni della sorgente, la direzione della freccia della sorgente di corrente punta sempre verso il terminale positivo della sorgente di tensione. Questa convenzione garantisce coerenza e aiuta a mantenere il corretto orientamento del circuito.

Tuttavia, vale la pena ricordare che la trasformazione della sorgente non è applicabile alle sorgenti di tensione ideali, poiché possiedono una resistenza interna pari a zero. Al contrario, le sorgenti di tensione non ideali presentano una resistenza interna diversa da zero, che le rende suscettibili alla trasformazione della sorgente. Allo stesso modo, le sorgenti di corrente ideali con resistenza interna infinita non possono essere sostituite con sorgenti di tensione finite.

Per illustrare l'applicazione pratica della trasformazione della sorgente, considerare un circuito collegato singolarmente a una sorgente di tensione non ideale (Figure 1) e a una sorgente di corrente non ideale (Figure 2). Quando la resistenza in serie è uguale alla resistenza in parallelo e la tensione ai capi della sorgente di tensione aderisce alla legge di Ohm, queste sorgenti non ideali diventano equivalenti tra loro.

<img alt="Figure1" src="/files/ftp_upload/15051/15051_PT_Figure_1.svg" style="text-align: center; height: 128px;">
Figure1: Circuito con una sorgente di tensione non ideale

<img alt="Figure2" src="/files/ftp_upload/15051/15051_PT_Figure_2.svg" style="text-align: center; height: 128px;">
Figure 2: Circuito con una sorgente di corrente non ideale

La sostituzione della sorgente di tensione non ideale con la sorgente di corrente non ideale equivalente non altera le caratteristiche di tensione o corrente di alcun elemento all'interno del circuito. Ciò dimostra la potenza della trasformazione della sorgente nel semplificare l'analisi del circuito senza influenzare il comportamento generale del circuito.

Trasformazione della sorgente

La tecnica di trasformazione della sorgente consente la conversione di una sorgente di tensione in serie con un resistore in una sorgente di corrente equivalente in parallelo ...

Education

Didattica

JoVE Core

Electrical Engineering

Ingegneria elettrica

Unit 1

Unità 1

DC Circuit Analysis

Analisi dei circuiti in CC

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

Source Transformation

circuit source equivalents

Circuit source equivalents make it easier to simplify electrical circuits in circuit analysis. A source transformation replaces a voltage source in series with a resistor by a current source in parallel with a resistor, or it replaces a current source in parallel with a resistor by a voltage source in series with a resistor.

The key idea is that the equivalent resistance at the circuit terminals stays the same when the original sources are turned off. When making the change, the current source arrow must point toward the positive terminal of the voltage source. This keeps the circuit orientation consistent.

Source transformation does not work for ideal voltage sources because they have zero internal resistance. It also does not work for ideal current sources because they have infinite internal resistance. Nonideal voltage sources and nonideal current sources can be transformed because their internal resistance is not zero or infinite.

The transcript shows this idea with a nonideal voltage source and a nonideal current source. When the series resistance matches the parallel resistance, and the voltage across the voltage source follows Ohm's law, the two sources are equivalent. Replacing the nonideal voltage source with the matching nonideal current source does not change the voltage or current in any circuit element.

Circuit Source Equivalents

nodal analysis

Using Node Voltages in Circuit Analysis

Nodal analysis uses node voltages to simplify circuit analysis. In this method, the voltage at each node becomes the main variable. Once those voltages are known, they can be used to find other values, such as the current through specific circuit parts. The process begins by choosing a reference node, also called a datum node. This node is selected for convenience and assigned a voltage of zero. The other nodes, called non-reference nodes, are then measured relative to that point. In the...

nodal analysis with voltage sources

Supernode Equations in Nodal Analysis

Nodal analysis uses node voltages and Kirchhoff’s laws to solve circuits with voltage sources. It is a systematic method for breaking a complex circuit into smaller parts that are easier to analyze. In this example, the circuit includes four resistors and two voltage sources. One voltage source is connected between a non-reference node and the reference node. In that case, the non-reference node voltage can be written directly as the source voltage. This removes one unknown and makes the...

mesh analysis

Mesh Currents for Circuit Analysis

Mesh currents give students a simpler way to analyze planar circuits. In mesh analysis, the unknowns are currents, not voltages. The method uses Kirchhoff's voltage law, or KVL, to build the equations needed to solve the circuit. A mesh is a closed loop in a circuit that does not contain any smaller loops inside it. Each independent mesh is assigned a mesh current, and this current is usually drawn in the clockwise direction. These mesh currents are used as the main circuit variables during...

mesh analysis with current sources

Current Sources in Mesh Circuit Analysis

Current sources make mesh circuit analysis easier because they can reduce the number of equations needed. This applies to both independent and dependent current sources. The method depends on where the current source is placed in the circuit. When a current source appears in only one mesh, the setup is simple. Assign mesh currents as usual, but leave out the mesh that contains the current source from the equation process. Then apply Kirchhoff's voltage law, or KVL, to the remaining mesh to get...

source transformation

Circuit source equivalents make it easier to simplify electrical circuits in circuit analysis. A source transformation replaces a voltage source in series with a resistor by a current source in parallel with a resistor, or it replaces a current source in parallel with a resistor by a voltage source in series with a resistor. The key idea is that the equivalent resistance at the circuit terminals stays the same when the original sources are turned off. When making the change, the current source...

linear circuits

Circuit Linearity and Resistor Behavior

Circuit linearity describes how a circuit responds when its input changes. A linear circuit has an output that is directly proportional to its input. This behavior follows two rules: homogeneity and additivity. Homogeneity means that if the input, or excitation, is multiplied by a constant factor, the response is multiplied by the same factor. For example, if the current is increased by a constant k, the voltage also increases by k times. Additivity means that the response to a sum of inputs...

superposition theorem

Analyzing Circuits with Superposition

Superposition is a circuit analysis method for linear circuits with more than one independent source. It lets you find the voltage across or current through an element by adding the separate effects of each source acting alone. To use superposition, keep one independent source active and turn off the others. A voltage source is replaced by a short circuit, and a current source is replaced by an open circuit. Then calculate the output from the single active source. Repeat the process for each...

thevinin's theorem

Thevenin Circuit Equivalents

Thevenin circuit equivalents simplify linear two-terminal circuits by replacing the fixed part of a network with one equivalent source and one resistor. This method is useful when a circuit has a fixed section and a load that can change. A household electrical outlet is a familiar example, because different appliances can be plugged in or removed. Each change in load can require a new circuit analysis, so an equivalent circuit makes the work easier. Thevenin's theorem states that a linear...

norton's theorem

Norton Equivalent Circuit in DC Analysis

Norton equivalent circuit in DC analysis shows how a linear two-terminal circuit can be replaced by a simpler network. The replacement uses a current source, called I_N, in parallel with a resistor, called R_N. I_N is the short-circuit current through the terminals, and R_N is the input or equivalent resistance seen at the terminals when the independent sources are turned off. To find Norton's resistance, all independent sources in the circuit are set to zero. The resistance measured at the...

maximum power transfer

Load Matching in Thevenin Circuits

Load matching in Thevenin circuits helps a source deliver the most power to a connected load. This matters in engineering fields such as telecommunications, where power delivery must be optimized. Even then, internal losses can be significant and may equal or exceed the power sent to the load. The Thevenin equivalent circuit is a useful way to study this situation. It replaces the full linear circuit with a simpler source and resistance while keeping the load in place. In this setup, the load...

design example: strain gauge bridge or wheatstone bridge

design-example-strain-gauge-bridge-or-wheatstone-bridge

Wheatstone Bridge Output for Strain Gauge Design

A strain gauge and Wheatstone bridge work together to turn mechanical strain into an electrical signal. In engineering, this setup is often used to measure force or pressure. Each part of the bridge has a resistance that changes slightly when strain is applied. The main goal is to turn a very small voltage output into a larger, easier-to-read signal. A voltmeter can then measure that output more clearly. To do this, an engineer designs the strain gauge circuit and figures out how much...

key terms and concepts

Learn how source transformation replaces nonideal voltage and current sources while keeping terminal resistance the same in circuit analysis.

Circuit Source Equivalents | 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 Equivalents

Description

Transcript

Tags