The superposition principle and the Thevenin force apply to that kind of circuit

Suitable for linear circuits.

This is because the independent source is linearly related to the branch current or branch voltage.

The Davenin is used to find the output voltage.

It is also used in mold electricity to output resistors as balls.

Thevenin's theorem is to network a single-ended network into an equivalent resistance and a voltage source.

The principle of superposition is simple, in a circuit with a lot of power supply, you have to analyze the circuit, so that a single power supply can work, other power supplies do not work, in this case, the voltage source is regarded as a short circuit, the current source is regarded as an open circuit, so that the circuit analysis is greatly simplified, of course, you have to analyze all the situations of each power supply alone, and the final result can be a simple superposition. By the way, controlled sources do not participate in the overlay.

This is how to analyze circuits. Not a way to design a circuit...

Linear circuits. There is no reason for ...

It's like you ask why 1+1=2

The branch current method is the most basic analysis method, which is suitable for any form of circuit, but it is more complicated; The superposition theorem can decompose the calculation and analysis of complex circuits with multiple power supplies into the calculation and analysis of multiple single-supply circuits, but the overall steps are generally not simple. For circuits with special structures and solution objects, the junction voltage method and Thevenin's theorem are the methods to simplify the analysis.

If the circuit analysis can be simplified by equivalent transformations, it is best to perform the corresponding equivalent transformations first. For circuits with two nodes and multiple branches connected in parallel, or can be partially equivalent converted according to conditions, it is more convenient to use the junction voltage method. In the case of finding only a certain branch current or voltage, applying Thevenin's theorem is undoubtedly the easiest.

1. Conditions for the use of Thevenin's theorem.

1) Thevenin's theorem is only equivalent to external circuits, not to internal circuits;

2) When applying Thevenin's theorem for analysis and calculation, if the active two-terminal network after the branch is still a complex circuit, Thevennan's theorem can be applied again until it becomes a simple circuit.

2) Thevenin's theorem only applies to linear active two-terminal networks.

2. The conditions for the use of the superposition principle.

1) The superposition principle is only suitable for the voltage and current of the buried linear circuit, and is not applicable to the power;

2) When each independent power supply acts alone, the other independent power supplies do not work, the voltage source is short-circuited, and the current source is disconnected;

3) When superimposing, we should pay attention to the voltage and the reference direction of the current, and pay attention to the positive and negative aspects of the voltage component and the current component when summing.

Superposition principle use conditions] The specific use conditions of the pose slide are:

1. Only linear circuits have superposition, and the principle of superposition cannot be applied to nonlinear circuits.

2. Only the independent power supply can be zeroed, and the circuit containing the controlled source should not be forced to take the zero value when using the superposition principle. This is because once a controlled source is forced to zero, it is equivalent to undoing the envy of the physical element represented by the controlled source in the circuit, resulting in an erroneous result.

3. The power cannot be calculated by the principle of superposition.

4. When a power supply does not work temporarily, the power supply is set to zero. For independent voltage sources, they are shorted at both ends when they do not work temporarily, and for independent current sources, both ends are opened.

Conditions for the use of Dai Wenning's theorem] is also known as: Thevenin's theorem. The specific conditions of use are as follows:

1) Thevenin's theorem is only equivalent to external circuits, not to internal circuits; In other words, it is not possible to apply the theorem to find the equivalent power supply electromotive force and internal resistance and then go back to find the current and power of the original circuit (i.e., the internal circuit of the active two-terminal network).

2) When applying Thevenin's theorem for analysis and calculation, if the active two-terminal network after the branch is still a complex circuit, Thevennan's theorem can be applied again until it becomes a simple circuit.

3. Thevenin's theorem is only applicable to linear active two-terminal reticulated waxing networks. If there are nonlinear components in the active two-terminal network, the Thevenin theorem cannot be applied.

4. The proper selection of Thevenin's theorem and Norton's theorem will greatly simplify the circuit.

1. Conditions for the use of Thevenin's theorem.

1) Thevenin's theorem is only equivalent to external circuits, not to internal circuits;

2) When applying Thevenin's theorem for analysis and calculation, if the active two-terminal network after the branch is still a complex circuit, Thevennan's theorem can be applied again until it becomes a simple circuit.

2) Thevenin's theorem only applies to linear active two-terminal networks.

2. The conditions for the use of the superposition principle.

1) The superposition principle is only suitable for solving the voltage and current of the linear circuit, and is not applicable to the power;

2) When each independent power supply acts alone, the other independent power supplies do not work, the voltage source is short-circuited, and the current source is disconnected;

3) Pay attention to the reference direction of voltage and current when superimposing, and pay attention to the positive and negative of voltage component and current component when summing.

This is the third of the five major algorithms used by the electrician profession to solve the problem I don't know what you want to express

Solution: Davenin: Disconnect r=4 from the circuit, and the left and right ends are a and b respectively.

3. The current of the resistor is the current source current 7A, then the voltage is: U1=7 3=21(V), left positive and right negative.

So: uoc=uab=u1+us=21+35=56(v).

Then the voltage source is short-circuited and the current source is opened, and the req=3 is obtained.

Therefore: i=uoc (req+r)=56 (3+4)=8(a).

When the superimposed A current source acts alone, the 35V voltage source is short-circuited. The branch of 2 parallel 1 is also short-circuited.

The voltage at the source of the current is: U=7 3 4=12(V).

So: i'=u/4=12÷4=3（a）。

When the V voltage source acts alone, the 7A current source is open.

There are no two parallel branches outside the voltage source, one is (2+1) and the other is (3+4), so: i"=35/（3+4）=5（a）。

3. Superposition: i=i'+i"=3+5=8（a）。

The superposition is self-reliant, and when 2V acts alone, 3A is set to open the circuit, baii1'=2/4=，v'=(-2i1x3)+2=-1v；

When DU3A acts alone, 2V is set to short circuit, i1"=0，v"=3x3=9v；v=v'+v"=

Davy DAONAN: Move away from 3A current source, i1=2 4=,UAB=(-2I1X3)+2=-1V; A,B is short-circuited,I1=2 4=,A,B short-circuit current isc=2 3-2i1=-1 3 A,Rab=UAB isc=3 ohms; The equivalent circuit of Thevenin is UAB string Rab, which is moved forward from 3A to A, B, V=(3X3)-UAB=8V.

The superposition theorem is that when there are two or more power supplies in a circuit, if the parameters of a certain branch are required, the parameters of each power supply acting on this branch can be found separately, and then their algebraic sum can be obtained.

Thevenin's theorem is: In the current at a more complex point, when finding the parameters of a certain branch, this branch can be proposed, and then the other parts of the circuit can be equivalent to a voltage source and a resistor in series. This is a simple calculation.