An electronic system is made up of electronic units, each unit carrying out a particular job on the electronic signal as it passes through the system. Electronic units, in turn, consist of one or more conductive circuits and these are made up of electrical and electronic components connected together so that when a voltage source is applied to the circuit an electric current flows from the source, to and through the circuit and back to the source. If the source is a direct current source the current flow is in one direction (conventionally from positive to negative—but electrons flow in the opposite direction) and if the source is an alternating current source the current flow changes direction periodically. Components and materials used for connecting them are considered in more detail later; for the moment we must examine the basic ways of connecting components together. The component which will be used as an example is one with which most people are familiar, a small lamp similar to a torch bulb, which could be used for indicating purposes in a circuit.
Unable to display preview. Download preview PDF.