| 摘要 |
PURPOSE:To simplify decision on the cause of a trouble with a smaller scale in the manufacture of a false circuit by employing a resistor and a differential amplifier for the electromagnetic force generating mechanism, a D/A converter as weight to be placed on a balance plate and an LPF as balance. CONSTITUTION:The weight to be placed on a balance plate is set as desired with a digital setting device 13 and a weight equivalence is converted into a voltage eD with a D/A converter 14. The voltage across a resistance 15 is amplified 16 to obtain an output voltage eF. A differential amplifier 17 computes difference (eD-eF) between two inputs and the output thereof is led to a terminal A through a secondary LPF 18 having a shielding frequency characteristic virtually equal to the response frequency of a balance beam. In the false electronic balance of such a type, the loop system made up of circuits 17 and 18, a PID controller 6, the resistance 15 and a circuit 16 operates to always meet the requirement of eD=eF. |
