The Pointer of the Sequencer rotates toward each of its four sides in sequence at a user-specified speed, sending out a Redstone signal as it passes each side. The Sequencer does not have an input side, only the four output sides, which means it cannot be turned off. Right-Click with a Screwdriver to rotate and Shift-Right-Click to make the pointer go in the opposite direction.
Because Sequencers are synced to world time, any action which causes a change in the world time (like sleeping in a bed, or using the /time command) will cause the Sequencer to change state. In some designs, this will have little-to-no effect, but if a Sequencer is used to manage time-sensitive circuits, it may cause bugs in the circuit design.
Since it is synchronized to world time, it makes a handy clock - simply set it to 300 seconds. It can constantly switch on and off machines, pistons, etc.
- Putting a Sequencer next to a Lamp and connecting two of the facing outputs together will result in two cables where one will switch on and the other is then always off. This function may prove rather useful to power Nuclear Reactors and other dangerous machines that need to be switched off on a regular basis.
- Sequencers can also be used to coordinate different parts of the same system. For example with an Automatic Wheat Farm you can have three of the Sequencer's outputs connected to each other and then to an Assembler which is set to perform three actions in sequence; Hoe, Plant, and apply Bone meal. Then you can tie the fourth Sequencer output to a Block Breaker (which will harvest the wheat, making it ready for the start of the Assembler's sequence again). So for each of the 4 outputs on the Sequencer you are doing the following; Hoe, Plant, Grow, Harvest.