| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a low frequency AC current detector which can detect an AC current of frequency within a specified range with a simple circuit. <P>SOLUTION: A frequency detecting means 202 is equipped with a first monostable multivibrator 20 which outputs a second pulse having a pulse width being set beforehand under detection purpose frequency at fall of the above first pulse when the first pulse geared to the frequency of AC components is inputted, a second monostable multivibrator 7 which outputs a third pulse being set beforehand over detection purpose frequency at fall of the above second pulse when the above second pulse is inputted, an integrator 8 which outputs a value being obtained by integrating the above third pulse, and a comparator 9 which compares the above integrated value with a preset detection level and outputs a detection signal of the above low frequency AC current when the above integrated value has reached the the above detection level. <P>COPYRIGHT: (C)2004,JPO |
