A one minute redstone timer. Very simple using one command block, one stone block, one pressure plate, one dispenser, one redstone torch, and some dust. Now that is the final working timer. You need to trigger it to start the process. Just press the button first, then destroy the button and replace it with a redstone torch. After every minute the arrow, one or two, shoot down at the pressure plate and lock the redstone signal for another minute. There will be eight or nine arrows left in the dispenser every time. To disable the timer, remove the arrows from the dispensers then remove the torch, or just break the dust link.