Proximity switch with class=C oscillator transistor - has oscillator controlling charging and discharging of capacitor that operates trigger

摘要

The proximity switch has an oscillator whose oscillations can be damped. It has a demodulator, a threshold switch and an output stage. The active transistor (Q2) of the oscillator is driven in the class-C mode. This transistor determines the charging and discharging of a capacitor (C4), and the charge state of the capacitor operates a single transistor (Q3) in the threshold switch. The oscillator transistor is in parallel with the capacitor.