Uni - Junction transistor

NPN - Photo transistor

PNP - Photo transistor

Audio frequency transistor

Amplifier the signal

Converts voltage into current

Produces electrical noise signal

Defects the operation of switching signal

0.5 V

0.8 V

2 V

2.5 V

Aluminium sulfide

Cadmium sulfide

Zinc sulfide

Copper sulfide

DC circuits

AC powered circuits

Amplifier circuits

Counter circuits