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AC Pick-Offs

  • Overview +

    A pick-off is an angle sensor, which can be small and light in weight.

    'Pick-offs are variable reluctance devices, having an unwound (solid or laminated) rotor. The rotor construction can be solid or laminated assembly. The stator has a single energising winding and a single output winding, namely primary and secondary. When energised the primary, the rotor movement disturbs the field created by the primary at a given voltage and the frequency, producing the output in the secondary. This output voltage varies in linear proportion to the rotation angle from a zero, or reference, position but only over a limited range from zero. In other words, the output voltage is proportional to the rotation angle. It can be designed in two or multi-pole versions and are inherently brushless, a feature that makes them suited to miniature applications. Typically, multi-pole devices have better accuracy over two pole versions. Furthermore, the maximum angular range of operation is dependent on the number of poles but not on the size of the device.

    These devices give an AC output signal, the magnitude of which varies with the angle of rotation over a maximum range of ± 45 degrees.

    The input and output windings on the stator represent a single phase

    We typically use AC pick-offs where ratio-metric signal conditioning is not required but where weight reduction and general simplicity are paramount requirements.

    Please refer to our range of rotational variable differential transformers (RVDTs) and Resolvers for devices capable of providing more accurate data over a more comprehensive angular range.

    We supply pick-offs for many applications, including monitoring the inlet guide vanes for gas turbine engines and as part of a seeker's head for an anti-tank missile.

  • Applications +

    • AC Pick–Off for Flight Critical Position Data
      The unit shown in the picture monitors the position of an engine's inlet guide vane and transmits the data to the pilot's display.
    • Pick–Off for Missile control Gimbals
      Where low mass and rotor inertia are key design factors, the design of these devices can provide a solution with an optimal electromechanical response.