Probe having passive means transmitting an output signal by reactive coupling

摘要: Apparatus for monitoring the state of a first circuit (19) by means second (29) has an inductive coupling (23) linking circuits across gap (32). The embodies oscillator (27) producing primary oscillations in that and, through coupling, secondary (19). If is changed as opening or closing contacts (17,18), resulting change impedance results frequency and oscillations. connected to detector (35) signal (37AI) when changes. Instead capacitative may be used. apparatus described applied machine measuring length. embodied probe (12) whereby workpiece measured. opened such contact. head on which releasably mounted. Since passive one, does not need independent power supply, supply serves any one mounted head.