| 摘要 |
PURPOSE:To increase the flexibility in design by leading emitters of two transistors (TRs) of a current mirror circuit feeding back a current to a resonance circuit as terminals, and connecting an external resistor to them so as to vary the vibration mode freely. CONSTITUTION:A current is fed back to a parallel resonance circuit 1 comprising a detection coil 2 and a capacitor 3 via a current mirror circuit of a bipolar monolithic IC 20. An emitter of a TR 12 of TRs 12, 13 of the current mirror circuit is led out as a terminal T at the outside of the IC 20, and a resistor 16 is mounted externally to the terminal T, hard vibration is caused in the circuit 1 and in connecting the emitter of the TR 13 is led out as a terminal to which an external mounted resistor is connected, soft vibration is caused. Thus, the vibration state is varied freely without replacing the bipolar IC and the design flexibility of the proximity switch is improved.
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