Abstract: A meter measures a voltage across a quasi-diode, the voltage caused by a current flowing through a resistance which changes substantially exponentially with changes in a medium being sensed. The meter comprises a logarithmic current measuring circuit coupled to the resistance to provide a measurement output that is a logarithmic function of the current flowing through the sensing resistance. A switchable current source is controlled by a switching circuit to repetitively output first and second current values. A reference logarithmic circuit is connected to the switchable current source and is physically coupled to the logarithmic measuring circuit so as to be maintained at a substantially equal temperature value. The logarithmic reference circuit manifests a first voltage in response to the first current value and a second voltage in response to the second current value, both voltage values dependent upon the temperature of the logarithmic reference circuit.