CPC H03K 17/954 (2013.01) [H03K 17/9545 (2013.01); H03K 17/955 (2013.01)] | 19 Claims |
1. A proximity switch comprising:
an oscillating circuit configured to detect carbon based on a change in amplitude of a detection signal,
wherein the oscillating circuit has a resonant frequency in a range of from 0.8 MHz to 20 MHz,
wherein the oscillating circuit comprises a first pair of coils, a second pair of coils, and a capacitor,
wherein the first pair of coils includes a first transmitting coil and a first receiving coil, and
wherein the second pair of coils includes a second transmitting coil and a second receiving coil.
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