Conrad Course material 10127 14 years and over 10127 Manual De Usuario

How the transistor works 
A small current applied to the basis-emitter section can control a large 

current on the collector-emitter section. I.e. if a low basis current is flowing 

(positive in NPN transistors, negative in PNP transistors), the transistor 

will conduct the current from the collector to the emitter or vice versa. If no 

current is flowing through the basis or if the basis connection is with negative 

(NPN) or positive potential (PNP), the transistor will block. 

 

Fig. 008: Circuit symbols for NPN and PNP transistors.

A resistor is a passive element in electrical and electronic circuits. Its main task is 

reduction of the flowing current to sensible values (also see chapter  

»Light-Emitting Diodes«).
The best-known resistor build is the cylindrical ceramics carrier with axial  

connection wires.