| 摘要 |
PURPOSE:To detect the presence of an open detection coil by providing an oscillation transistor (TR), a DC bias circuit giving a bias to the oscillation TR and the detection coil, connecting a resonance circuit to a DC bias circuit in series so as to detect a DC bias current. CONSTITUTION:In receiving an on-signal output of a TR Q11, a fault output circuit 10 regards the detection coil L1 as normal and outputs no fault output to an output terminal 11. On the other hand, if the detection coil L1 is opened, no bias current flows to a bias circuit 3 by a TR Q2. Thus, a TR Q7 is turned off, no current flows to a TR Q9 and no current flows to a TR Q10. When no current flows to the TR Q10, the TR Q11 is turned off. When the fault output circuit 10 receives an OFF signal output of the TR Q11, the detection coil L1 is discriminated to be faulty and a signal representing a fault is outputted from the output terminal 11.
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