| 摘要 |
<p>A servovalve has a sensor for sensing the movement and indicating the position of the valve spool (1). The sensor comprises a ferrite core (5) mounted upon an extension (4) of the spool (1), and a pick-up coil (6) connected into the circuit of a Colpitts oscillator whose output drives, via a voltage limiter, a phase lock loop integrated circuit (IC2). The output of the circuit (IC2) is connected to a phase comparator (IC3) to produce a control signal whose amplitude represents the frequency of oscillation of the oscillator.</p> |
