5 min redstone timer

This is the timer that I use in my escape the room maps http://www.planetminecraft.com/project/escape-the-prison-puzzle-map-181/
It times for exactly 5 mins and is based off the fact that item drops take exactly 5 mins to decay
If something similar has been uploaded, I have not seen that, and have not copied off that person

You need to add an inverter at the end of each timer, and one extra timer at the end without and inverter to stop the device being turned on before the timer is started. I would also reccomend adding an RSNOR latch at the end to stop the signal resetting after 5 mins

http://ad.cx/2fr495 MCedit Schematic Download Link