A Golden Weighted Pressure Plate act as a Door opener.
Put items on top and a door opens.
To reset the system I have to remove the items somehow from the Plate. I tried a Hopper to suck the items when the exact amount activate the Plate.
In snapshot 13w02a switches on top of hoppers had no effect of the hopper,
but in 13w02b this was fixed
But now if you place a Weighted Pressure Plate on top of a disabled Hopper, you can't suck the items from the Plate into the hopper, when you cut the power.
Because two mechanics block each other; Pressure Plate give a signal by one item, hopper accept turn-off signal from the top.