Abstract text

A method and instrument capable of accurately detecting the presence of a gas and accurately measuring the concentration of the gas in, for example, the environment. The method and instrument sense the presence of a gas with a sensing element whose output is linear to the concentration of the gas in the environment, and process the output of the sensing element through a nonlinear amplifier having a higher gain at lower levels of the output than at higher levels of the output so that the nonlinear amplifier amplifies the output of the sensing element at the lower levels thereof and avoids signal saturation at the higher levels thereof. The method and instrument then deliver the amplified output of the nonlinear amplifier to an audio circuit that produces an audio output having a property in proportion to the amplified output of the nonlinear amplifier.