This is how to keep the trouble of zombies breaking down your door.....

Items
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Daylight Sensor
Sticky Piston
Stair
Glass
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Step one..... dig a hold 2 deep
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Step two... place piston at bottom of hole facing up
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Step three... place stair
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Step four........ by the hole dig two down
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Step five....... place daylight sensor at bottom
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Step six... place glass on the block level with ground
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Then your DONE! wait till night and see what happens!

Enjoy!