Transcript No Slide Title

The NPN transistor as a circuit element
NPN-Transistor
Transistors Replace Mechanical Switches
“Tin Can”
Collector
Base
Emitter
NPN-Transistor
Transistors are constructed differently and this fact is reflected in the names that are
given to the pins. As a first pass at this technology, it will not hurt to associate the
names in pairs.
The 1960’s transistor
However, ultimately the
operational principles for the
pins with similar names is not
the same for different types of
transistors.
The “Tin Can”
it isn’t tin and
it isn’t a can!
Base OR Gate
Emitter OR Source
Collector OR Drain
NPN-Transistor
Bipolar Junction Transistor
Silicon structure with a shortage
of electrons in its structure
p-type material
Silicon structure with extra
electrons in its structure
n
p
n
Silicon structure with
extra electrons in its
structure
Emitter
n-type material
NPN-Transistor
Ground
connection
This switch now controls the light.
Bipolar Junction
Transistor
If it is
closed, the light will go on.
If this switch is
closed, the light
will turn on if
the switch in
the base circuit
is closed.
Simple Switching Circuit Example
Emitter
n
negative
terminal
p
n
positive
terminal
Ground
connection
Ground
connection
NPN-Transistor
Ground
connection
Bipolar Junction Transistor
Simple Switching Circuit Example
electron flow
Emitter
negative
terminal
positive
terminal
Ground connection
Ground connection
NPN-Transistor
Ground connection
Another view of the npn transistor switch circuit
positive
terminal
Emitter
Ground connection
negative
terminal
Ground connection
NPN-Transistor
This new cartoon is a little closer to
reality since it includes a drawing of a
real npn transistor with its correct pin
locations.
Ground connection
positive
terminal
Emitter
Ground
connection
negative
terminal
Ground connection
Ground
connection
NTE 198
Notice that the
base connection is
not in the middle
of the device
package even
though inside the
package the base
is in the middle of
the device.
Negative
terminal
positive
terminal
Ground
connection
NPN-Transistor
Base
Negative terminal
Collector
Emitter
NTE 198
positive
terminal
Ground
connection
NPN-Transistor
Base
Negative terminal
Collector
Emitter
positive
terminal
Ground
connection
Base
Negative terminal
Collector
Emitter
positive
terminal
Ground
connection