Common Input Components

Question 1

Toggle switch

Symbol
Characteristics
Uses

Answer 1

Symbol:
/
/
—0 0—

Characteristics:

• off and on positions
• once switched they stay latched until switched again

Uses:

• lighting
• power switch
• control panels

Question 2

PTM switch
Characteristics
Uses

Answer 2

Push to make switch
Normally open

C:
The legs only connected when switch pressed
Normally open
No polarity

Uses:
Door bell
Intercoms
Keyboards

Question 3

PTB switch
Characteristics
Uses

Answer 3

Push to break switch
Normally closed

C:
Legs disconnected when switch pressed
Normally closed
No polarity

Used:
Alarm systems
Control systems

Question 4

LDR
Characteristics
Uses

Answer 4

Light dependent resistor

C:
Resistance increases in dark, decreases in light
No polarity

Uses:
Street lights
Solar garden lights 
Security and child night lights
Low light meter for sporting events

Question 5

Thermistor
Characteristics
Uses

Answer 5

Characteristics:
Resistance changes with change in temperature
No polarity

Uses:
Thermostats on central heating
Fridges / freezers
Digital thermometers

Question 6

Pressure switch
Characteristics
Uses

Answer 6

Characteristics:
detects pressure from being pressed

Can perform on/off tasks
Detects gradual pressure being applied

Uses:
Burglar alarm systems
Video game floor mats
Sensing fluid 
Pressure in pipes