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

The source transformation technique enables the conversion of a voltage source in series with a resistor into an equivalent current source in parallel with the resistor or vice versa.
During transformation, the resistor values in the circuit remain the same. Using Ohm&#39;s law, the values of voltage or current can be determined.
The arrow of the current source always points toward the positive terminal of the voltage source.
This technique cannot be applied to ideal voltage and current sources due to their internal resistance characteristics.
Consider a circuit consisting of a voltage source, a current source and some resistors. Using source transformation, the voltage drop across the central resistor can be determined.
Initially, apply source transformation in both sources to obtain the reduced circuit.
Now transform the left voltage source again into a current source. The circuit is further simplified into a single current source configuration.
Using the current division formula, the current through the resistor is obtained. By substituting it in Ohm&#39;s law, the voltage drop across the resistor is obtained.

source transformation

Source transformation is a fundamental technique employed in circuit analysis, offering a valuable tool for simplifying complex electrical circuits. This technique involves the replacement of either a voltage source in series with a resistor by a current source in parallel with a resistor, or vice versa. The key concept here is that when the original sources are deactivated (turned off), the equivalent resistance at the circuit's end terminals remains the same.
It is essential to note that when performing source transformations, the direction of the current source arrow always points toward the positive terminal of the voltage source. This convention ensures consistency and aids in maintaining proper circuit orientation.
However, it is worth mentioning that source transformation is not applicable to ideal voltage sources, as they possess zero internal resistance. In contrast, nonideal voltage sources feature non-zero internal resistance, making them amenable to source transformation. Similarly, ideal current sources with infinite internal resistance cannot be substituted with finite voltage sources.
To illustrate the practical application of source transformation, consider a circuit connected to a non-ideal voltage source (Figure 1) and a non-ideal current source (Figure 2) individually. When the series resistance equals the parallel resistance, and the voltage across the voltage source adheres to Ohm's law, these non-ideal sources become equivalent to each other.
<img alt="Electronic circuit diagram with series resistor, voltage source, Circuit A; basic electrical analysis." src="/files/ftp_upload/15051/15051_PT_Figure_1.svg" style="text-align: center; height: 128px;" data-altupdatedat="1754904545000" data-alt="Electrical circuit diagram; voltage source \(v_s\) with resistor \(R_s\) connected to Circuit A." />
Figure 1: Circuit with to non-ideal voltage source 
<img alt="Electrical circuit diagram with current source Is, resistor Rp, connected to Circuit A for analysis." src="/files/ftp_upload/15051/15051_PT_Figure_2.svg" style="text-align: center; height: 128px;" data-altupdatedat="1754904545000" data-alt="Electrical circuit diagram showing current source \(I_s\), parallel resistor \(R_p\), and connected Circuit A." />
Figure 2: Circuit with to non-ideal current source
Replacing the nonideal voltage source with the equivalent nonideal current source does not alter the voltage or current characteristics of any element within the circuit. This demonstrates the power of source transformation in simplifying circuit analysis without affecting overall circuit behavior.

Source Transformation

Source transformation is a fundamental technique employed in circuit analysis, offering a valuable tool for simplifying complex electrical circuits. This ...

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JoVE Core

Electrical Engineering

Unit 1

DC Circuit Analysis

KEY TERMS AND CONCEPTS

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

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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...

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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

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