this is just  a command block clock blog

Setblock clock

Top command block /setblock ~ ~-1 ~ redstone_block 0 destroy

Bottom command block /setblock ~ ~1 ~ air

After puting the command in to the command block place a redstone block in the open space as shown in the pic
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Fill clock

Top command block /fill ~ ~-1 ~ ~ ~-1 ~ redstone_block 0 replace stone

Bottom command block /fill ~ ~1 ~ ~ ~1 ~ stone 0 replace redstone_block

After puting the command in to the command block place a redstone block in the open space as shown in the pic
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