This is the second volume of a two part series, and a companion to Investigating Electronics Vol 1. Divided into three sections, the authors begin with simple circuitry detecting light, heat and fluid and then discuss the construction of logic gates. Part two provides a detailed explanation of multivibrators, including bistables and flip flop circuits. Part three investigates digital microelectronics: integrated circuit logic gates; integrated circuit multivibrators; shift registers; adder circuits and counters.