Who didn’t dream of a hidden door or secret passage in the house when they were kids? Some of us still do! [SPECTREcat] had already built a secret door in a fully functioning bookcase with a unique opening mechanism. The intriguing mechanism allows the doors to start by sliding slightly away form one another before hinging into the hidden space. Their operation was, however, was manual. The next step was to automate the secret door opening mechanism with electronics.
The project brain is an off-the-shelf Arduino Uno paired with a MultiMoto Arduino shield to drive 4 Progressive Automations PA-14 linear actuators. These linear actuators have 50lb force, allowing the doors to fully open or close within 10 seconds and maintain a speed that wouldn’t throw the books off the bookcases.
Not wanting to drill a hole through the bookshelf for a switch or other opening mechanisms, [SPECTREcat] added a reed switch that is activated on the other side by a DVD cover with a magnet inside. In addition to that, there is a PIR sensor on the inside room to automatically close the doors if no motion is detected for 2 hours. Dont worry, there’s also a manual switch inside just in case.
Using one of the items on the shelf to trigger the secret passage is a classic move. He could also have used a secret knock code, like the Secret Attic Library Door we covered in the past. Check out the video below to see the hinge and slide movement in action.
Secret Porn Layer
OSI Layer 8: the Secret Porn layer
Nice! Not very safe in case of fire, though
Just wait until the fire burns down the wooden bookshelves.
Yep. Highly illegal, and not just because of the doors, but also because there don’t appear to be any windows in the room itself.
That’s a death trap, ladies and gents.
Battery backup and a connection to the fire alarm will solve that. Any electric door in a commercial building without a breakaway function has to have one.
Review of the Instructables page shows that it has an emergency egress function.
Nice movement, yes, but it sounds like a Stuka. It’s not going to be a secret for long.
ehmmm… promoting it on youtube doesn’t help in keeping it a secret either, does it?
But despite the fact that the secret door is no longer a secret, it looks sooooooooo cool.
Easy solution: have it blare your theme music at a deafening volume upon activating the door. Anyone asks, just tell them you want to *feel* the music!
PWM the actuators so, theme music in stereo.
http://hackaday.com/2014/01/05/the-most-beautiful-floppy-disk-jukebox-ever/
It should play the “secret discovered” tune from Zelda 1 when it opens.
“Mr Smith I need you!”
The movement and action is great.
But the noise?
Anyway to make it quieter.
No problem—just evacuate all of the air in the room.
That would suck… breathing would be a big issue.
The noise is coming from the actuators being so tightly coupled to the wood. Cork/rubber gaskets between the actuator and its mounting surfaces will quiet that down radically.
nice little primary action on the opening but I have to ask, with almost $1200 spent on just the linear actuators, why not a $10 enclosure for the controller?
perhaps he ran out of money?
I also thought it’s way too expensive, so here are some links to making your own linear actuators:
http://hackaday.com/2016/03/31/3d-printed-case-turns-servo-into-quality-linear-actuator/ (We need more 3D printed articles like this; need to scale it up…)
http://hackaday.com/2014/04/12/diy-linear-actuators-for-a-flight-sim/
http://hackaday.com/2011/10/09/linear-motor-can-be-built-from-trash/
http://hackaday.com/2010/01/19/servo-hacked-linear-actuator/
Window lifter mechanisms apparently work great as well, and they are relatively quiet.
I’ve been looking at those over in the UK for automating my windows.
Here they are insanely expensive. Over in the US it seems you can get them at discount DIY stores.
There isn’t a Chinese option either which makes it cheap.
As mentioned above: use window ‘regulators’. You’ll have to pop off some door panels, and should probably bring along a gel cell 12v battery+leads to test the motor, but they work great.
It looks cooler with its guts in the open.
so stealthy! ;)
Did not know those linear actuators were that noisy. But I do now.
Learnin’ is goood!
I’m thinking the same thing could have been done on a rope and pulley system much more elegantly – and more cheaply.
First of all, there’s no need for the doubled up motors because a mechanical linkage can pull the shelves apart as the door is being swung open in one action. You don’t need to first separate the shelves and then open the door – it can open as the door swings.
I’m not so familiar with Yankee units but I didn’t think lb was a measure of force.
Yeah, that doesn’t seem right. Probably the maximum lift limit of the actuators.
pounds force is a measurement of force (lbf). Sometimes it just gets shortened to pounds. Kinda sorta like people using grams instead of mN.
I always thought a pound was a force unit. Sticking an “f” after the “lb” is redundant.
There is actually pound force (lbf) and pound mass (lbm). They have the same numerical value (on Earth, if you’re looking at weight). Pound force (lbf) is the natural unit for force in the imperial system, and pound mass is NOT the natural unit of mass (that would be the slug – 1/32.17 pound mass).
This right here is the problem with the imperial system. All other problems are liveable, but when you have to infer from the use whether it’s mass or force, just because someone got lazy and wrote lb instead of lbf or lbm, there is a problem.
Is this a CRT TV?
Probably… some of us still have them.
Me, haha.
The ‘ol hinged first book at a convenient height. With regular use the floor and one worn and smudged book wouldn’t fool Sherlock Holmes or Agent 77. Make it a reference book?
Note his handle: [SPECTREcat]. I believe he and his organization are contractually obligated to leave clues to enable 007 to find the secret control room in a timely fashion.
Great idea, and +1 for Get Smart reference.
On another show…
Columbo would ‘accidentally’ bumble into it, triggering the mechanism. Or he would talk about all the interesting books and make the suspect sweat. ;)
Should have added the sounds the doors make in Hitchhikers Guide To The Galaxy :)
I am guessing the clock in the bookcase is battery operated.
A spring powered pendulum would probably not work.
Now he just has to heat the room so he doesn’t have to wear his jacket in the house.