| 摘要 |
<p>PURPOSE:To detect grounding and to attain one line actuation, by detecting the grounding of a subscriber line with the output of a comparator means in a subscriber circuit feeding power to the subscriber line from the power supply at a station in floating state. CONSTITUTION:As a comparator means, a comparator COMP, a series resistor RC, and a preset reference potential VDET are used. The comparator COMP usea a voltage generated across the resistor RC as one (+) input, and compares a feedback current I1 with the VDET set the other input (-), and when the I1 exceeds a prescribed value and the voltage drop across the RC exceeds the reference voltage, the comparator COMP outputs a signal from an output terminal OUT. Thus, grounding of a subscriber line as a failure, grounding at one line start by grounding one of the subscriber lines with key operation at a telephone set, are detected through the presence of the signal at the OUT.</p> |
