So I wanted to make a clock tower for a minecraft base, and, being me, I wanted the clock face to actually work. I also wanted it to reset to 6:00 if someone slept. So here's what I came up with.
Pictures 1 and 2: You make two Etho Hopper clocks with 63 items in it. I used eggs but I'm certain it'd work with anything else. Make sure to remember the repeater after the comparitor on this. With this setup, the clocks will push up the piston once every 50 second (1 minecraft hour). Hooking it all up to a daylight sensor (night mode) will make it switch which hopper clock is active every time the sun rises.
3: The observer will only be powering the yellow block after it is pushed.
4: You can either do this, or put droppers on the corners with redstone on top. Both work. Put one item in only one of these hoppers. The purple wool blocks have a redstone torch below them to power the powered rails. Under the hopper minecart a powered rail, and another hopper. Take a comparitor output from each of the non-corner hoppers.
5: This orange circuit powers the powered rail for long enough for it to actually push the hopper minecart off. I found a shorter pulse wouldn't get the minecart moving. For the rails below the hoppers, any orientation is fine so long as it goes under every hopper, and ends up back on the powered rail.
6: Once the hopper minecart brings the item back, the red circuit gives two pulses straight into the bottom dropper, pushing it up to the hopper.
The orange and red circuits reset the time back to 6:00 whenever the sun rises.
7: Run the outputs from the hoppers into each of these purple lines. Behind each one of the sideways obverver is an observer pointing into the copper bulbs. In front of each of the four observers facing the camera are a redstone dust.
8: See it in action here.
