The alarm system is used to keep burglars and unwanted people out of one's home.

If you cross the trip wire behind the door, the alarm system is activated and you hear an alarm sound. The alarm system can be deactivated via a lever.

Instructions:

The first thing to do is to build note blocks into the ceiling as in the picture above.



On this picture you can see how often you should click on the note blocks (My suggestion is to click on the first three [here on the right] 5 times, and on the last two 20 times).



Directly behind the door leading into the corridor, place two hooks on the walls and place a thread between them.



Now lay a Redstone wire from the hook (which is on the other side of the wall), as shown in the picture, up to the ceiling. The gap between the two Redstone amplifiers is intentional, because there will be a small circuit with which you can turn the alarm system on and off.



This is the redstone line with which you reset the alarm system. I just put it there, you can then lead it to where you want to reset the alarm system. As you can see, I also put two normal pistons and a redstone block between the circuits now. The redstone block will make the clock turn off again.



The orange redstone line is the on/off button mentioned above. When the plunger is in the extended position as shown in the picture, the redstone signal is routed from one redstone amplifier to the other. I think you can see everything from the picture, you can then route this circuit to where you want to turn the alarm on and off. Here again a picture from inside, I used a lever here. If you want, you can also use a flip-flop, then you can switch the alarm system on and off from several places.





This is the clock that drives the audible signal. In the picture this is just turned off because the redstone block is powering the block that the redstone flare is attached to, thus turning the flare off. The two redstone amplifiers are set to two ticks, as you can see in the picture.



Now connect the note blocks to the clock, and set redstone amplifiers in between. The two right ones are set to two ticks, the two left ones to three.

Now you only have to activate the alarm system with the orange redstone line, and if someone enters the door and runs over the trip wire, the alarm goes off. You can reset it with the yellow redstone line. If you have any questions you can contact me or just write a comment. I hope you like it.

LG,
jusi12345