1. Systems and Control

2. What is a System?
A system is a set of devices or things which are connected and work in conjunction with each other in order to perform a specific function.

3. All systems have
PROCESS
INPUT
OUTPUT

4. Example:

5. PROCESS
INPUT
OUTPUT

6. A system is sometimes made of subsystems joined together.
INPUT
Door sensor
Burglar Alarm
INPUT
Window sensor
PROCESS
OUTPUT
Siren Flashing light
INPUT
Panic button

7. INPUT
Input sensors usually convert a change in light, movement, temperature or humidity into changes in electrical signals.
The inputs are often tiny changes of voltage, current or resistance.

8. PROCESS
The process or processor is the part of a control system which reacts to the inputs.
The changes to the inputs are usually too small to operate output devices like buzzers or motors, so they have to be amplified to give a large enough change to operate the output devices.

9. Processing Device Example
Amplifiers
Amplifies small inputs
Electronic switches
Switches at different levels
Timers
Switches after time delay
Counters
Counts input pulses
Computers
Detects signals from inputs
Micro-processors

10. OUTPUT
Output devices are those which convert electrical signals into sound, light or movement.
Output Device
Example
Lamps
Light
Buzzers/Bells
Sound
Speakers
Motors
Movement
Indicators
Information