Electronic systems consist of:
· An input device to sense changes, e.g. a light detector
· A processor that responds to the change
· An output device that enables the system to do something useful.
· There may be feedback to control the response of the circuit.
We can represent this very basic idea with a block diagram:
Now try Question 1, Question 2, and Question 3.
A Circuit diagram tells us:
· How the components are laid out and wired up.
· Engineers use circuit diagrams to assemble the circuit.
· It uses standard symbols with which you need to be familiar.
· The lines represent the copper tracks on the circuit board. Where the lines are connected there is a black dot, to represent a blob of solder.
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Now try Question 4
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This is a block diagram for a domestic burglar alarm.
With a block diagram we can split a complex system into a number of smaller sub-systems.
Often a complex circuit is built on several boards with each sub-system or module on a separate board. This has several advantages:
- The circuit boards can be built and tested separately.
- If the circuit goes wrong, the defective module can be easily removed without having to replace everything else.
- Modifications can be made more easily.
Here is a simple block diagram of a train sound system that might be used for a model railway.
The wiring diagram shows the power supplies to the components of a circuit.
- The way the wires are connected between the components.
- The way the wires may be in looms
- The colour of the wires
There are some points that we can note for all electronic circuits:
- Most electronic circuits use low voltage dc.
- Most electronic circuits cannot give out a lot of power.
- There are ways of interfacing low voltage circuits with high power outputs.
- Often power supplies are omitted from circuits for clarity, but it is essential that they be put in when we build the circuit. The pin-out diagram shows the power supply as well as all the other connections.