| 摘要 |
PROBLEM TO BE SOLVED: To make an invariably stable continuity check by making a resistance value determining continuity constant. SOLUTION: A resistance bridge circuit 16 is used which has a resistance 11 as one of four sides connected to a low-impedance circuit 19 whose continuity should be detected in parallel, and also has reference low resistors 12 and 13 forming one side adjacent to the mentioned side and resistors 14 and 15 with the same resistance value forming the remaining two sides, and the output of this resistor bridge circuit is inputted to a comparator 21, which compares the resistance of the low-impedance circuit 19, the resistance of the parallel circuit including the resistor 11, and the resistance values of the reference low resistances, so that a light emitting diode 25 illuminates and a buzzer 26 sounds responding to the comparator output when the resistance value of the parallel circuit is less than the resistance value of the reference low resistors.
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