| 摘要 |
PURPOSE:To measure water content region covering wide range automatically, by converting current, which passes through a specimen, directly to a logarithm without branching out in a low water content region and also by executing the logarithmic conversion through a branch-out circuit by an automatic switch circuit in a high water content region. CONSTITUTION:A couple of electrodes Ea and Eb, which contain grains of specimen, are connected to an oscillator 1 and an operation amplifier IC1 of a branch- out circuit 2. Output of the operation amplifier IC1 is connected to an analog switch SW1 of a semiconductor. Analog switches SW1-SW4 are provided with a movable contact ai and fixed contacts bi and ci (i=1-4), and at first, a1, b1, a2, b2... are connected to form a high water content measuring circuit. A current and voltage logarithmic conversion circuit 3 is composed of an operating amplifier IC2 and diodes D3 and D4, and current passes through a resistance R2. The current enters an operation control circuit 5 through the switch SW4, which is connected between a4 and b4, and a voltage buffer circuit IC3, and in case when a water content signal is determined to be that of low water content, the switch SWi (i=1-4) is connected between ai and ci. |
