I'm making a minigame where a player has to survive in essentially a world of hell. I am creating a "water bar", where players must drink to survive. It is a dummy scoreboard objective. I want to run the command "/scoreboard players @p remove water 1" every 3 minutes so players can run out of water. The current loop I have is a circle loop (https://i.ytimg.com/vi/0c-NGRXY5u0/maxresdefault.jpg) but much bigger than the one shown. Is there a way I can make a loop that's much smaller than the one I have currently but still sends a signal to the command block once every 3 minutes?
You'll have to work out the math a bit, but a non-command block slow clock I like to use basically uses an And Gate with two asynchronous loops of redstone, with a single tick pulse going in circles until they both hit the And Gate at the same time. For example a loop of 10 ticks and a loop of 11 ticks set off at the same time will not line up until 110 ticks. Normally 110 ticks of delay would be over 27 repeaters, but using the two loops only costs 6 repeaters. You can dramatically increase duration by using a third loop, however finding the correct tick counts involves a bit of math; using a spreadsheet like Excel helps a lot.
Edit: I just did the math in Excel, because I love math, Excel, and redstone haha. One (there can be other possible solutions this is merely the first one I found by randomly typing in numbers) solution is 49 and 75 tick loops, which is 13 and 19 repeaters. These will only line up after 3675 ticks, which at 20 ticks a second is 183.75 seconds or basically just slightly longer than 3 minutes.
For comparison to achieve that long of a delay with just repeaters on their own you would need 919 repeaters. 32 repeaters or 919 repeaters...a clear choice to me!
You can make a slow clock quite easily with a minecart and cobwebs. Make a track that runs uphill and then falls onto cobwebs. For every cobweb you place, the minecart will take 30 more seconds to fall. Then, at the bottom, put powered rails and 1 detector rail to send out a signal, then connect that track to the one running uphill to make a loop.