Electronics 01
Transistor Base Resistor Calculation: Use Forced Beta
Dividing load current by hFE gives a base resistor that leaves many transistors half on. Size it for a forced beta of 10, with worked 2N2222 and BC547 examples.
transistors
Electronics 02
How Does a Transistor Amplify? It's a Valve, Not a Source
A transistor doesn't make energy: a millivolt on the base steers current from the supply. Transconductance, gain = gm × RC, and a worked common-emitter design.