Abstract: A scanning control system is disclosed for remotely sensing or monitoring a predetermined condition or state, such as the presence of a fire, by means of one or a multiplicity of detecting stations at one or a multiplicity of locations with each detecting station providing a positive indication of the location of each predetermined condition sensed. A scanning or control panel is electrically connected with the detecting stations by means of four wires extending from the panel regardless of the number of detecting stations utilized in the system.

Abstract: A smoke detection apparatus is disclosed having a highly efficient ionization chamber. The ionization chamber is primarily formed by a wire mesh collector that readily admits products of combustion such as smoke into the chamber which has therein an alpha emitting, radioactive source and a selectable portion of a tuning screw. Two types of smoke detectors are shown utilizing the ionization chamber with one of the detectors operating from a conventional A.C. power source and the other being battery operated. The smoke detector utilizing the conventional A.C. power source requires no transformer and has the alarm indicating horn connected with the A.C. source with the horn being triggered by a silicon controlled rectifier connected with the radioactive source in the ionization chamber through a field effect transistor switch. A rectified and regulated D.C. voltage is provided to the wire mesh collector and to the field effect transistor switch.