Process Subsystems

 

The process part of a system is at the heart of the system and needs to respond to the input sensors, or triggers and automatically control the operation of the system's output devices(s).

A semiconductor transistor is an ideal component to do this. As its name suggests, it can either act as a conductor or an insulator.

pic of transistor

In its simplest arrangement we can think of the transistor as an electronic control switch going between "on" or "off".

pic of black box with actual switch

Its ability to be one of two states makes it perfect for handling digital (1's and 0's) information. As such, millions of transistors are embedded in the processors found in more complicated systems such as computers or smart phones.

Operation of the Transistor

In FastTrack we are thinking about systems rather than individual components and circuits.We will therefore be using the "black box" approach and putting the components and circuits into boxes representing the different subsystems.

Although the theory of the transistor is covered in greater detail in the Tutorials section and OnTrack, all we need to know here is most transistors will switch on the output subsystem when it is provided with a "turn on" voltage that is greater than 0.6 volts.

pic saying an example of a safety light were a darkness sensor provides 0.6 volts at the transistor's input when it gets to required level of darkness. The transistor then automatically turns on an led. ( Use centre subsystem as a circuit and pic of led and sun etc to show courtesy light system and the 0.6 volts required. Have animation of slider going darker and 0.6 -v appearing and led coming on.

Adding a few extra components to the transistor subsystem, provides extra control possibilities. These are shown to the sides. In the next section we will see ways in which the input stage provides the transistor with the necessary "turn on" voltage of 0.6 volts.