Using a Block Update Detector (BUD), I was able to create a secret entrance contraption to open a secret bookcase.

This map only contains the skeleton of the contraption, and only demonstrates how it is used.
There isn't a house built to show it's full extent, but it allows users to see how it is built, and how it works.

A Block Update Detector is built, as well as a redstone clock to give time to pass through the entrance.

I don't care if this is used in your own way. But please do not re-post this map as your own.

Noobish Instructions:
1.When you finish extracting the map file in your saves folder, open the map.

2.You will spawn and see the contraption and how it works, take a look.

3.To use it, open the chest and see what happens.

4.When exiting the pressure plates are the exit pads.

5.Experiment with this contraption.