Switches
Electronics 1
CVHS
Basic Elements of a
Circuit
• Three Essential Elements
– Load
– Complete Path
– Power Source
• Additional Elements
– Control Device
– Protective Device
Electricity Generation
• Six Methods Used to Produce Electricity
– Chemical
– Magnetism
– Heat
– Friction
– Light
– Pressure
Basic Switch Function
• To open and close a circuit
–Open (no connection)
–Closed (connection)
• Control device
–Does not consume power
Schematic Terms
• Pole- what the switch
armature is connected to
• Throw- the closed position of
the switch
Pole
Throw
Single Pole, Single Throw
• SPST
• 1 pole, 1 throw
• Example- room lights
SPST Animation
Single Pole, Double Throw
• SPDT
• 1 pole
• 2 throws, 2 closed positions
SPDT Animation
Double Pole, Single Throw
• DPST
• 2 poles
Double Pole, Single Throw
• Not 2 throws because of
mechanical connection
• Both armatures make contact at
same time- one closed position
DPST
DPST Animation
Double Pole, Double Throw
• DPDT
• 2 poles
• 2 separate closed positions
DPDT Animation
Switch Styles
Toggle
Slide
Switch Styles
Rocker
Push On/Off
Other Switches
• Momentary contact switches
–Push button switches
• Rotary switches
Momentary Contact
• Push Button Normally Open
• PBNO
• Red in color
PBNO
Momentary Contact
• Push Button Normally Closed
• PBNC
• Black in color
PBNC
Rotary Switches
• Used for complex circuits
• Can have multiple throws
Rotary Switch
• Example- Stereo input selector
#1)
?P?T
#2)
?P?T
#3)
?P?T
#4)
?P?T
#1)
3P1T
#2)
2P5T
#3)
3P2T
#4)
3P3T
Review
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•
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•
What are the three basic parts of a circuit?
What else can a circuit include?
What are the six sources of energy?
What is the main function of a switch?
What is the difference between a throw and a
pole?
• What other types of switches are available?