Diode circuit: load line concept, clipping circuits, comparators, sampling gate, rectifiers, capacitive filters, additional diode circuit. Transistor: the junction transistor, transistor as an amplifier, transistor construction, the CE configuration, the CB configuration, the CE cut-off and saturation region, common emitter current gain, the common collector configuration, analytical expression for transistor characteristics, the photo-transistor. Transistor at low frequency: graphical analysis of the CE model, two-port model and hybrid model, transistor hybrid model, the h-parameter, analysis of transistor amplifier circuit using h parameter, the emitter follower, miller's theorem and its duality, cascading transistor amplifiers, simplified CE and CC configuration.