LESSON 05 – COMBINATION CIRCUITS

LESSON NOTE

A combination circuit is simply a circuit that contains loads in series and in parallel.

EXAMPLE 1

In the following combination circuit, an electron first goes through one of the branches in the parallel section and then goes through the light bulb (in series). If an electron has to go through more than one load, it is going through a series of loads (series circuit).

EXAMPLE 2

In the following combination circuit, an electron first goes through two light bulbs and then through one of the parallel branches.

EXAMPLE 3

The following combination circuit consists of two parallel sections that are in series.

EXAMPLE 4

The following combination circuit consists of a parallel section. One of the branches consists of two loads in series.

PROPERTIES OF COMBINATION CIRCUITS

The properties are simple. Sections that are in parallel are dealt with using the rules of parallel circuits. Sections that are in series are dealt with using the rules of series circuits.

SOLVING TECHNIQUES

There are two approaches to solving such problems.

One approach is to use the single table like before. However, the columns in such a table no longer follow strictly series or parallel rules. You will have to use analysis to figure values when you are stuck.

Another approach is to use a multi-table system. Essentially, you create a different table for each sub-series or sub-parallel section. This involves a fair bit of extra writing but allows you to continue solving the tables like before.

We will look at both approaches in the examples.