Bipolar Junction Transistor which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base). BJT transistors are made for DC current because are unidirectional (one-way current).
NPN Transistor
Circuit:
Vcc to Collector
GND to the Emitter
Voltage from 0v to 5v (swich off - swich on) to the Base
Between Vcc and Collector
PNP Transistor
Circuit:
Vcc to Emitter
GND to the Collector
Voltage from 0v to Vcc (swich on - swich off) to the Base
Bipolar Junction Transistor which the current flow between two terminals (the collector and the emitter) is controlled by the amount of current that flows through a third terminal (the base). BJT transistors are made for DC current because are unidirectional (one-way current).
NPN Transistor
Circuit:
PNP Transistor
Circuit:
References
Defference between NPN and PNP (Spanish)