21/08/2012
An Electronics System
All electronics systems contain
INPUT, PROCESS and OUTPUT.
Input (device) – changes some form of
energy into an electrical signal
Process – electrical signals are processed
(eg amplified) by transistors or logic chips
Output (device) – converts an electrical
signal into another form of energy
Signal Types
Signals can be Analogue or Digital.
Analogue Signals – vary constantly between
a maximum and a minimum value and can have
any value in between
Mercury thermometers, microphones, solar
cells, win-up watches are analogue devices
Digital Signals – have only two possible
values; on/off high/low 1/0 5V/0V
(note there are no values in between)
Digital thermometers, digital clocks,
switches, strip lights are digital devices
An Example of An Electrical System
A microphone connected to an amplifier and loudspeaker
INPUT
microphone –
converts sound
energy to
electrical energy
PROCESS
OUTPUT
amplifier
loudspeaker –
converts electrical
energy to sound
energy
CRO Traces of Analogue and Digital Signals
Analogue
Digital
1
0
1