CHOKE DETECTING CIRCUIT FOR RADIATION MEASURING INSTRUMENT USING SEMICONDUCTOR DETECTOR

摘要

PURPOSE:To permit detection of a chock condition of a measuring system by detecting the voltage drop of a load resistor connected to a bias power supply for supplying bias current to a semiconductor detector which generates pulses by detecting radiations and comparing the same with a chock detection value. CONSTITUTION:The load resistor 5 is connected to the power supply side of the bias power supplying 1 for supplying the bias current to the silicon semiconductor detector 2 and the current flowing in order to replenish the electric charge generated by the generator 2 is detected by an amplifier circuit 7 for amplifying the voltage drop across the resistor 5 and is converted by an LPF 8 to a DC voltage. This converted voltage is compared by a comparator 10. The output of the comparator 10 inverts and the choke detection signal is outputted from an output circuit 11 when the converted voltage attains the set value by a choke detection setter 9 or above. The choke condition of the measuring system which arises under high radiation is thereby detected and the erroneous measurement occurring in the choke is prevented.