Redstone: Player Detectors

Description

I know like the majority of the master redstoners already know this... When I am playing an adventure map, I get horrified by all those events controlled by those pressure plates. Seriously, Minecraft is 1.5! Like how the npcs talking is controlled by pressure plates. Seriously? Why not a player detector for your adventure maps?

How it works

This is VERY simple. A command block testing for a player at certain amount of radius with a redstone clock, and the comparator sending signal to whatever you want to be activated when a player approaches. It activates a piston which will stop the redstone clock so it wouldn't keep doing the same thing when the player re-approach.

So please stop using those derpy activators if you can, and start using this Player Proximity Detector.