Hi gang! Before I begin I'd like to start by sharing that it was Dramanya who first introduced me to the concept of a "torch lock" after she build something similar within our outpost of Regen. This is a simpler (and somewhat easier) format. Also: the examples shown here were made in singleplayer, but they still pretty much apply to the Empire as well. Be careful when building this together with others though, because block protection can become an hindrance if a piston owned by player 'A' needs to shove (protected) blocks owned by player 'B'. What are you not seeing here? If you're building in an area which has a low roof and isn't all too big then this simple 2 piston door mechanic could be just the thing for you to keep your base secure and hidden, while still keeping it easy to enter. There's nothing special about the screenshot above, but as soon as I place a redstone torch on the top right block then you'll notice something special: Ignore the sandstone block for now please The two blocks move to the back and reveal a hidden area. And because they moved back the torch which I placed automatically drops to the ground and can be easily picked up while entering this hidden room. So how does this work? Simple... the main thing you need to know is that a redstone torch is actually a (redstone) power source. And in the example above its placed directly under a block. Because of that the block above the torch gets "strongly powered". Which means so much that every redstone (dust) around that block will automatically pick up this charge. Here's an example: The torch (strongly) powers the block above it. And because of that the redstone dust next to the block also gets powered and lights up. And we're going to use that charge to open up the door. Of course there's one problem... The power of the torch opens the door. But as soon as the door opens and the torch gets dropped it will also stop powering the block. So the door would immediately close without giving you an option to enter. But that's where the "2 comparator delay" comes into play: I replaced all the netherrack blocks which have redstone dust on top with sandstone blocks, so that they're easy to recognize. As you can see I use a redstone torch to power the block behind the top piston, this results in both pistons getting triggered. I made a hole in which I placed a redstone repeater, this ensures that a redstone charge will power the repeater which will turn the torch off (and make the pistons retract, which opens the door). By placing the two comparators like this you're actually generating an interesting effect: a slow power degradation. The original redstone signal goes into the left comparator. At the end it moves towards us which powers the block next to the repeater, but it also powers the comparator on the right. Here's where things become interesting: the comparator on the right is 1 block next to the original. This may seem unimportant, but every redstone signal degrades by one for every block it needs to travel. So if the signal is 15 after it leaves the left comparator, then it'll be 14 when it enters the right comparator. It will also be 14 when it exits the right comparator, but now it gets send back into the left comparator again. This means that if the original power source (the torch) is gone, then the left comparator (which keeps the door open) will still be powered. But instead of 15 it now gets an input signal of 13. Which will eventually turn to 11, 9, 7 and so on. That will create just the delay you'll need to quickly pass the door, after which it'll automatically close. Another closer look at how you'd place the torch Here I removed some blocks to clearly demonstrate what's going on. I place the torch on the door, and this will power the block above it (which I've removed in the above screenshot). Because it is strongly powered it would automatically charge the redstone next to it, which opens the door. So how do we get out? Simple! By placing the same redstone torch again, but this time on the inside of the door: When I place the torch on the netherrack (where the cross points to) then the torch will power the redstone dust on the floor, which in its turn opens the door. The torch will drop, and you can easily pick it up as you leave the room. The same cycle is put into effect: the redstone signal slowly degrades and eventually the door will close again. But then you'll have easily left the room. And there you have it! As said it's a bit simple and easy. You're going to have to get used to walking over redstone components, but as a result it takes up very little space, and you'll always be able to enter as long as you have a redstone torch on you. Just make sure you remember where you need to place it I hope this can be useful for some of you.
I foresee a future full of nosy people spamming redstone torches right and left in the hope of uncovering secret doors... reminds me of when we used to play D&D in our young age (yes, right when the dinosaurs got extinct), with the elf and the thief scanning every hooks and crannies of every wall of every dungeon... So many D6 rolled for nothing...
Alternatively you could place the redstone torch on the lower block of the wall. A piston under the floor would be activated, leading to stuff happening. Reasoning here is that (only) pistons will be activated if the block 2 blocks above it is powered.
