Analysis of Combination Circuits

Circuit analysis is the process of solving a circuit in order to determine voltage across, or current through the elements of the circuit.

The basic technique used for solving combination-circuit problems is the use of equivalent circuits. To simplify a complex circuit to a simple circuit containing only one load, equivalent circuits are substituted for the complex circuit they represent.

Often, we may determine the currents and voltages for each element in a resistive circuit by repeatedly replacing series and parallel combinations of resistances by their equivalent resistances. Eventually, this may reduce the circuit sufficiently that the equivalent circuit can be solved easily.

Analysis Procedure for Series-Parallel Resistor Circuits:

1. Draw a circuit diagram identifying all components by number and showing all currents and voltage drops.

2. Start by locating a combination of resistances that are in series or parallel. The ideal place to start is farthest from the source.

3. Redraw the circuit with the equivalent resistances for the combination found in step 2.

4. Repeat steps 2 and 3 until the circuit is reduced as far as possible. If possible, we should finish off with a single source and a single resistance.

5. Solve for the current and voltage in the final equivalent circuit, preferably by applying Ohm’s law.

6. Transfer results back one step and solve for additional unknown currents and voltages. Again transfer results back one step and solve.

7. Repeat the steps until all of the currents and voltages are known in the original circuit.