ABSTRACT
A fire alarm circuit, as its name implies, sounds an alarm in the event of a fire. There can be one or several alarms throughout a building, and there can be several alarm points which activate the warning. The alarm points can be operated manually or automatically; in the latter case they may be sensitive to heat, smoke or ionization. There are clearly many combinations possible, and we shall try in this chapter to give some systematic account of the way they are built up. The external circuitry is similar whether the control panel consists of electronic components or electromechanical relays.
