Proximity detector for objects on production line - has oscillator sensitive to presence of objects and feedback capacitive threshold redressing stage from detector head to oscillator

摘要

A proximity detector circuit (DP) is supplied with an alternating current and comprises an oscillator (OSC) sensitive to the presence of objects to be detected in the vicinity of the detecting head (UA). A redressing stage (AL) provides feed back from the detecting stage (DP) to the oscillator (OSC) and comprises an accumulating condenser for supplying the oscillator. Circuit interruptors (SW1) and (SW2) control the charge level of the feed back circuit according to preselected threshold values.