NPN. If the base is at a higher voltage than the emitter, current flows from collector to emitter.
NPN. Small amount of current also flows from base to emitter.
NPN. Voltage at base controls amount of current flow through transistor (collector to emitter).
PNP. If the base is at a voltage than the emitter, current flows from emitter to collector.
PNP. Small amount of current also flows from emitter to base.
PNP. Voltage at base controls amount of current flow through transistor (emitter to collector).
Follow the arrow to see the direction of current flow.
To figure out which is which when you're reading a schematic, remember this:
Not Pointed iN (NPN) Arrow points away from junction.
Pointed iN. (PNP) Arrow points toward junction.
