| 摘要 |
PURPOSE:To discriminate the presence of open wire based on a level of a DC component as a result of an input signal of an amplifier section eliminated with its high frequency component by applying a DC voltage to a connecting line. CONSTITUTION:If there exists an open wire in the connecting line 3 or a coil L, connecting points a, b reach a potential equal to that of a DC power supply E. Then, the potential is increased more than that at normal state. The voltage change between the normal state and the open wire is detected by a DC discriminating section 61, which gives an output to an open wire informing section 62. The open wire informing section 62 informs externally the state of open wire by a device such as buzzer or lamp. The resistance value of a resistor R1 should be selected large so as to decrease the effect on an oscillating section 2. On the other hand, if the resistor R1 is too large in its resistance value, since the sensitivity of the detection of open wire at the DC discriminating section 61 is affected, the resistance value should not be too large. |
