TRANSIENT_SWITCH_SIGNAL_SUPPRESSOR

Published:2009/7/17 2:30:00 Author:Jessie | From:SeekIC

The figure shows a circuit that delays the transmission of a switch-opening or switch-closing signal until after a preset suppression time. The circuit is used to prevent the transmission of an undesired momentary switch signal. For example, a pressure switch that is meant to be held steadily on or off by a given static pressure in a piping system can also be actuated momentarily by a transient overpressure (sometimes called water hammef') or underpressure caused by the sudden closure or opening of a valve. The basic mode of operation is simple. The beginning of the switch signal initiates a timing sequence. If the switch signal persists after the preset suppression time, then this circuit transmits the switch signal to the external circuitry. If the switch signal is no longer present after the suppression time, then the switch signal is deemed to be transient, and this circuit does not pass the signal on to the external circuitry. From the perspective of the external circuitry, it is as though there were no transient switch signal. The suppression time is preset at a value large enough to allow for the damping of the underlying pressure wave or other mechanical transient.



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