Learning out comes of this section
a transistor (npn) can be used as an amplifier.
a small base current will control a larger collector
current and that this is the basis of amplification.
the base current is large enough, the transistor behaves
as a switch such that the current in the collector can be turned on and
a transistor can be used as an oscillator to generate
audio and radio frequencies.
Know the difference between a crystal
oscillator and a variable frequency oscillator (VFO) based on a tuned circuit.