Abstract: The object of the present invention is the improvement of logarithmic amplifiers and/or converters and the applications of such devices in particular to photometric analyzer apparatuses.These amplifiers are characterized by the fact that they are linear with an amplification gain programmable by the .mu.P computer and that they may be preceded optionally by a reference voltage system.Application to the measurement of light transmitted by samples.

Abstract: The invention relates to an apparatus for the control and monitoring of a well head submerged in a liquid.The apparatus comprises electrovalve control means, an electronic system for controlling and monitoring the well head, monitoring sensors, connecting means connected to the electronic system and a station on the surface of the liquid medium using a transmission line. The electronic system comprises a first channel connected to the control means and to the sensors, supplied with electric power by the line and a second channel for controlling the control means and which is supplied with electric power by said line. The second channel and the electrovalve control means are also connected to an autonomous power supply, which is independent of the line. Each of the channels and the connection established bidirectional communications with the station.Application to the control and monitoring of submerged well heads.