Would you like to have a completely concealed secret room to protect your diamonds and emeralds from ... uh ... zombies?

Would you like to have a completely concealed secret room to protect your diamonds and emeralds from … uh … zombies?

This all started out as a project to demonstrate the Open Computers mod. Obviously, then, this post will not tell you anything about the Open Computers mod.

For some reason, that’s just the way I work. My PhD thesis followed essentially this same four-step pattern, just on a much grander scale.

  1. I get an idea.
  2. I research the idea.
  3. In researching the idea, I discover more fundamental ideas that must be researched before I can get back to my original idea.
  4. I pursue the new idea and never get back to my original idea.

You can actually chain multiple instances of this pattern together. In researching the new idea, it often happens that you discover yet even more fundamental ideas. My problem is that I am a big picture guy who nevertheless wants to nail down all the details. I just don’t see the details from the get go. So I am capable of coming up with ideas/projects of unimaginable complexity, thinking the whole time, “This should be doable.”

My wife, who was genetically engineered to be the perfect project manager, greets each new idea with a carefully controlled expression I have come to understand as a blend of interest and terror.

Fear not, however. I shall return to the Open Computers mod. For now, however, I want to talk about secret passages, piston extenders, and redstone pulse generators.

The Goal: A Secret Room With a Secret Door

The purpose of this build is to create an undetectable secret door whose opening mechanism is not visible. The means that I have to use pistons, and it means that the blocks being moved by the pistons must be flush with surface that surrounds them (so it is not obvious that they are a door). Now, you can, using six sticky pistons, make a door where two blocks retract and then move to the side. But for this project, I wanted to build a secret passageway into a staircase.

I want to give a shout out to YouTuber MrCubey for an outstanding instructional video on just this kind of staircase hidden door. MrCubey’s design makes conceals the triggering mechanism by making it so that you have to place down a button on a particular square. If I have one point of constructive criticism, it is that even with a wooden button, the window of time you have to pass through the door seems a little short. But that’s a minor point and one that many players wouldn’t have any problem with at all.

My design (which I worked out independently) works a little differently from MrCubey’s, so the dimensions end up being a little different. I think my Redstone setup is a little simpler, and it seems to be modestly more compact. Also, my larger design (which is, admittedly, not at all more compact than MrCubey’s) makes it possible to adjust the length of time the door stays open, AND you trigger it with a key item. I even went to the effort of making an amateurish video on my underpowered computer to demonstrate it.

Piston Extenders

An entrance like this requires the use of a piston extender (two pistons on top of one another)[picture]. This is easy enough to do, and I’ll show you below how it works. But this secret door also requires a single piston adjacent to the piston extender (we are retracting two diagonally adjacent stair blocks to make a two block high entrance we can walk through). Unfortunately, many of the piston extender designs I come across use all the space around the two pistons in order to keep the design compact (meaning we have no place to put one more piston). Two examples of this kind of piston extender can be seen in videos by TheRealMisterBam and Mumbo Jumbo. These are both fine designs, but they don’t serve our needs, in part because of their compactness. I feel that I have produced a design that solves this problem compactly and elegantly.

This is the area you will need for today's project. The gray blocks are for the basic piston mechanism. The red blocks show the space needed for the button triggers which we will use tentatively today.

This is the area you will need for today’s project. The gray blocks are for the basic piston mechanism. The red blocks show the space needed for the button triggers which we will use tentatively today.

This block is your input block. The lever will eventually not be needed.

This block is your input block. The lever will eventually not be needed.

Put down redstone and repeaters like this. Make sure the repeater on the right is on the longest interval (right click three times).

Put down redstone and repeaters like this. Make sure the repeater on the right is on the longest interval (right click three times).

Next, place a block over the first redstone torch. Place a second redstone torch over the right repeater like this. You will need a block above this torch. This is the floor level of the build, so it should be made of whatever material you want your floor to be made out of (that transmits a redstone signal, of course; so no glass).

Next, place a block over the first redstone torch. Place a second redstone torch over the right repeater like this. You will need a block above this torch. This is the floor level of the build, so it should be made of whatever material you want your floor to be made out of (that transmits a redstone signal, of course; so no glass).

Place three sticky pistons like this, all facing up.

Place three sticky pistons like this, all facing up.

When you flip the lever (redstone signal on) all three pistons extend.

When you flip the lever (redstone signal on) all three pistons extend.

Place stair blocks on the pistons, and you will see what this will look like when the secret door is concealed.

Place stair blocks on the pistons, and you will see what this will look like when the secret door is concealed.

The problem at this point is that, while the pistons retract completely, the stair block above the piston extender doesn't.

The problem at this point is that, while the pistons retract completely, the stair block above the piston extender doesn’t.

To solve the problem of the piston extender not fully retracting the second stair block, we have to add another part, which is essentially a pulse generator. There are lots of ways to do this, but this pulse generator is compact and serves our needs. Check out http://minecraft.gamepedia.com/Pulse_circuit for a very in depth article about pulse generators.

For our pulse generator, start by place a dropper above the input block, facing to the right.

For our pulse generator, start by place a dropper above the input block, facing to the right.

Place a single item in the dropper. It doesn't matter what the item is. I've used cobblestone.

Place a single item in the dropper. It doesn’t matter what the item is. I’ve used cobblestone.

Place a hopper feeding back into the dropper.

Place a hopper feeding back into the dropper.

Place a comparator next to the hopper. The block below the dropper receives a redstone signal, it will place the cobblestone in the hopper, causing the comparator to emit a redstone signal for just an instant (before the hopper feeds the item back into the dropper) that is carried to the top of the piston extender, causing it to extend and retract one more time.

Place a comparator next to the hopper. The block below the dropper receives a redstone signal, it will place the cobblestone in the hopper, causing the comparator to emit a redstone signal for just an instant (before the hopper feeds the item back into the dropper) that is carried to the top of the piston extender, causing it to extend and retract one more time.

The result of extending one more time is that the second stair block is now retracted two full blocks rather than just one.

The result of extending one more time is that the second stair block is now retracted two full blocks rather than just one.

Building out the rest of the staircase and the hidden room, it looks like this when door is open.

Building out the rest of the staircase and the hidden room, it looks like this when door is open.

A secret place to store your diamonds and emeralds and zombie flesh.

A secret place to store your diamonds and emeralds and zombie flesh.

When it is closed, the hidden room is completely undetectable.

When it is closed, the hidden room is completely undetectable.

The problem at the moment is that this mechanism is “off” by default, meaning the door is opened. That can be changed simply with a NOT gate (a.k.a., a redstone torch).

We add a redstone torch under the input block to change this from default "off" to default "on".

We add a redstone torch under the input block to change this from default “off” to default “on”.

Now, however, we need a way to trigger this door open. My larger project has you toss a key item onto the floor in front of the staircase. If you toss the wrong item, it simple spits it back out at you. If you toss the correct item, the door opens, and you receive your key item back inside the hidden room. But explaining all that is going to require a second post. So for this post I am going to show you how to use MrCubey’s button trigger with my piston setup.

Tentatively, we are going to use MrCubey's button trigger. To enter the room, you'll need to place a wooden button on this square and activate it. Be ready to move quickly.

Tentatively, we are going to use MrCubey’s button trigger. To enter the room, you’ll need to place a wooden button on this square and activate it. Be ready to move quickly.

From below, the outlined block is the one that holds the button. It is two blocks left and one block back from the piston.

From below, the outlined block is the one that holds the button. It is two blocks left and one block back from the piston.

Place a block two blocks below the button block and put redstone dust on it. This will activate when you push the button.

Place a block two blocks below the button block and put redstone dust on it. This will activate when you push the button.

Place another block diagonally down from the previous block (as shown) and place redstone dust on it.

Place another block diagonally down from the previous block (as shown) and place redstone dust on it.

Place another block diagonally down (so that it is below the first block) and place a repeater facing away.

Place another block diagonally down (so that it is below the first block) and place a repeater facing away.

Place blocks and redstone dust so that the signal leads into the side of the block containing the NOT gate redstone torch.

Place blocks and redstone dust so that the signal leads into the side of the block containing the NOT gate redstone torch.

Inside the room, place a button three blocks inside and one block to the side (away from the initial input block of the redstone mechanism below).

Inside the room, place a button three blocks inside and one block
to the side (away from the initial input block of the redstone mechanism below).

From below, the outlined block in the picture is the one that holds the button.

From below, the outlined block in the picture is the one that holds the button.

Place a block diagonally to the one containing the redstone dust of the pulse generator part of the original build. Put redstone dust on this as well.

Place a block diagonally to the one containing the redstone dust of the pulse generator part of the original build. Put redstone dust on this as well.

Place another block diagonally down and put a repeater on it facing away from the first block.

Place another block diagonally down and put a repeater on it facing away from the first block.

Place blocks, redstone dust, and one more repeater like this to connect the second button to the piston mechanism.

Place blocks, redstone dust, and one more repeater like this to connect the second button to the piston mechanism.

This is a picture of the whole redstone setup for today's project.

This is a picture of the whole redstone setup for today’s project.

In the next post, we will look a little more closely at how piston extenders work (retracting correctly usually involves what is called a redstone pulse generator). Plus, we will implement the key item triggering mechanism, which is, if I do say so myself, pretty darn cool.

 

Advertisements