Supervisory circuit for control signals - intended to reject spurious low value transient input signals uses delay element and level detector

摘要

The application is principally to protection or control circuits where signals coming from transducers may be subject to small transient disturbances, and where action of the circuit is to be inhibited is such cases. To introduce the required discrimination the signal arriving at the input terminal (4) of the additional circuit is passed through a delay element (1) which is followed by a level detector (2). Small disturbances are thus damped by the delay element and there is no response unless they persist. In that case the level detector setting is reached and a corresponding signal generated at the output terminals (6). Large changes in signal requiring immediate response bypass the delay element through a further level detector (3) and are applied immediately to the first level detector (2) thus appearing at the output terminals without delay.