This invention provides a simple vacuum level switch to be used inside the feedhead's vacuum plenum to detect when the vacuum level exceeds a predefined threshold. This switch is composed of an opening in the plenum that is covered by a cap which is in turn spring-loaded against the opening. The mechanical properties of the spring are such that the cap is pushed away from the opening by ambient air pressure at the point when the vacuum threshold has been reached during sheet acquisition. A Hall Effect or optical sensor is used to detect this motion and the corresponding signal is sent to the feeder controller. This enables more intelligent control of the feeder while also providing an inexpensive method for tracking sheet acquisition times.