Node-Voltage help. Is my equation right?

  • Thread starter LP20
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In summary, the problem is to find the voltage V_0 in the given circuit. The two nodes on the top can be treated as one, as well as the two bottom nodes. The node voltage equation for the circuit is -3 + V/200 + (V-5i)/10 + (V -80)/20, where V is V_0 and i is i sub delta (i_Δ). The dependent source in the circuit can be handled by rewriting i_Δ in terms of V_0 and constants. The only KCL equation needed for this circuit is the sum of all currents leaving the upper left node.
  • #1
LP20
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Homework Statement


Find Voltage V_0. There is also a dependent voltage source in the circuit I'm not sure what to do with.
The two nodes on top are essential nodes and can be treated as one, same with both bottom nodes, but the bottom nodes I assigned them to be the reference node.

Picture: http://img696.imageshack.us/img696/5396/1000948x.jpg

Homework Equations


The Attempt at a Solution


My node voltage equation : -3 + V/200 + (V-5i)/10 + (V -80)/20
V is V sub 0: V_0
and i is i sub delta i_Δ

For the equation for i_Δ : would it be (v-80)/20

Again I'm unsure of how to handle the dependent source in this circuit.
 
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  • #2
LP20 said:

Homework Statement


Find Voltage V_0. There is also a dependent voltage source in the circuit I'm not sure what to do with.
The two nodes on top are essential nodes and can be treated as one, same with both bottom nodes, but the bottom nodes I assigned them to be the reference node.

Picture: http://img696.imageshack.us/img696/5396/1000948x.jpg


Homework Equations





The Attempt at a Solution


My node voltage equation : -3 + V/200 + (V-5i)/10 + (V -80)/20
V is V sub 0: V_0
and i is i sub delta i_Δ

For the equation for i_Δ : would it be (v-80)/20

Again I'm unsure of how to handle the dependent source in this circuit.

There really is only one KCL equation for that circuit. You write the sum of all the currents leaving (or entering) the node at the upper left of the circuit (you are correct to call the bottom node the reference or ground node). Don't over-think this -- keep thinking currents. So for the right-hand leg, what is the current leaving out that way? Hint: No voltages are involved. Alternately, you can write i_Δ in terms of V_o and constants...
 
Last edited by a moderator:

FAQ: Node-Voltage help. Is my equation right?

1. What is the Node-Voltage method?

The Node-Voltage method is a technique used to analyze electrical circuits by assigning unknown voltages at different nodes and solving for their values using Kirchhoff's Current Law (KCL).

2. How do I choose the reference node for Node-Voltage analysis?

The reference node is usually chosen as the node with the most connections or as the ground node, where the voltage is known to be 0. This simplifies the equations and makes it easier to solve for the unknown voltages.

3. What is the equation used in Node-Voltage analysis?

The equation used in Node-Voltage analysis is KCL, which states that the sum of currents entering a node is equal to the sum of currents leaving the node. This can be represented as Σiin = Σiout.

4. How do I know if my Node-Voltage equation is correct?

To ensure that your equation is correct, you can double-check that it satisfies KCL by verifying that the sum of currents entering the node is equal to the sum of currents leaving the node. You can also compare your results with those obtained using other methods, such as the Mesh-Current method.

5. Can Node-Voltage analysis be used for any circuit?

Yes, Node-Voltage analysis can be used for any circuit, regardless of its complexity. However, it may become more challenging for circuits with a large number of nodes and branches, and other methods such as Mesh-Current analysis may be more efficient in those cases.

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