Transistor classification

a. By material: silicon tube, germanium tube

b. By structure: NPN, PNP. As shown in Figure 2:

c. By function: switch tube, power tube, Darlington tube, photosensitive tube, etc

d. According to power: small power tube, medium power tube, high power tube

e. According to the operating frequency: low frequency tube, high frequency tube and superfrequency tube

f. According to the structure process: alloy pipe, plane pipe

g. According to the installation mode: plug-in transistor, patch transistor