[Ressa]

...I need (okay, want) to know something that's going to get really technical and yucky for me. See, we're moving, and so I get to design a new room. I want an awesome Sherlcok-Holmes-esque room with large bookcases and overstuffed leather furniture. Anyway, one of my *dreams* is to have a chess board with magnetic pieces that, when positioned right, will trigger the clasp on a secret panel. I know, I know. Anyway, my dad is really awesome with mechanical stuff and I'm somewhat technically inclined, so I'm hoping it's not totally beyond impossible. I was just wondering if anyone knew of anyone who's done something like this, or if you know where would be a good place to start researching this topic.

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Since you want to use magnetic pieces, I can think of several ways. They do make some nice miniature magnetic switches which can be placed under each square. Then you can set up either a keypad or one using small switches to set your encoding for which pieces will close the correct switches to complete the circuit to open the panel. Encoding can be set to use, say, 4 or more switches required to be closed before panel opens.

All this can be miniaturized and placed inside the box. Even a rechargeable battery and circuit can be set up, where the battery can be charged like the pace makers' batteries... from the outside with an induction coil.

Sounds like a fun project and wish I was still doing electronics.

Ron

[Major Payne]

Since you want to use magnetic pieces, I can think of several ways. They do make some nice miniature magnetic switches which can be placed under each square. Then you can set up either a keypad or one using small switches to set your encoding for which pieces will close the correct switches to complete the circuit to open the panel. Encoding can be set to use, say, 4 or more switches required to be closed before panel opens.

All this can be miniaturized and placed inside the box. Even a rechargeable battery and circuit can be set up, where the battery can be charged like the pace makers' batteries... from the outside with an induction coil.

Sounds like a fun project and wish I was still doing electronics.

Ron

[dsenette]

if you didn't want to be that complex (i.e having to "code" a lock sequence) you could have the magnetic switches only on certain places on the board...then wire them in series (that doesn't look like i spelled it right)...so that they all have to be in the "on" position for the lock to open...of course most of this would require a relatively constant or at least easily maintained power supply....such as being plugged in or having a battery that's big enough to stay charged for a long time (I'd assume for the first month or so you'd be unlocking the secret panel every 5 minutes going "LOOK HOW COOL THAT IS!!!")
here's a crappy drawing of what i think would work


basically you have to have all 4 switches (or however many) in the on position for the circuit to be complete...when the circuit is complete you can have it fire a relay (which depending on the voltage used etc... this might not be needed....i just put it in there) that triggers a solenoid...the solenoid would push open the side of the box which is normally held closed with a magnet or two

[Ressa]

dsenette, that's exactly what I was thinking! I'm going to print out that "crappy" drawing you made to show my dad. I'm so excited to get started!

[dsenette]

something to think about...or for your pap to think about (that i didn't)....with the solenoid concept as i've laid it out....you'd have to have a way for it to turn off....the basics of what i just did would keep the solenoid on as long as the chess pieces are still in place.....if you move one of the pieces....then it would turn off

also most solenoids (if memory serves correct)....pull...instead of push....push types are available you just have to make sure you get the right time

you could also use a pull type if you had a latching mechanism on the inside of the door that was connected to the solenoid...when the solenoid fired it would pull the latch open...

either way it would probably be best to have a timer wired in somewhere....which would necessitate the relay because of voltage issues

[dsenette]

actually...the timer is stupid and overly complex! just put a N/O (normally open) momentary switch on the inside of the box in such a way that when the door is closed it will be fully depressed (i.e. closed)...wire that into the same circuit as the magnet switches...then when the solenoid pops the door open it will open the circuit thereby turning off the solenoid....then you'd have to move one of the chess pieces to close the door otherwise it would fire the solenoid again stopping you from closing the door

*dsenette smacks himself in the head for mentioning timers

i'm going to have to try to build something like this for my brother...he's getting married this month...hmm wonder how fast i could do this?

[Phenix]

That was a great sketch

[Ressa]

I was thinking along the same lines of using a latching solenoid with a momentary switch.../

If you finish this project for your brother within the month, you'd sure as heck better post step-by-steps for me!

[dsenette]

hehe well looking at my schedule it will probably be a christmas idea instead hehe..

if you're interested in the building and figuring out of random things (such as this) check out www.instructables.com it's a great community devoted to making things etc....very fun place to look around

all in all this one shouldn't be a difficult project...just a matter of building the box and wiring it up

[dsenette]

oh...and buying magnetic reed switches...i found some cheap ones on digikey (like $.7 a piece) but they had a minimum order of 1000....what would i do with 1000 magnetic reed switches?

[Ressa]

Instructables.com is actually how I came up with the idea of this project. I was searching around and found a cool hidden room project, you know, the kind where you pull on the book and the bookcase swings open.

With 1,000 Reed Switches...I suggest you give one to me (haha) and then you can make a thousand magnetic chess boards and sell them for profit!

[dsenette]

i wouldn't think you'd need a latching solenoid as there's no reason to hold the armature in any given state (except when the thing is "closed"....but that's when it's not energized so that shouldn't be an issue)

i found a bunch of small (low voltage) push solenoids as well

http://www.allelectr..._SOLENOID_.html
http://www.allelectr..._SOLENOID_.html
http://www.allelectr...20-067074_.html

none of these are spring return....but....closing the door on the box would return the armature to the original location once the power is cut (i.e. move one of the chess pieces before you close the door)

these are all 12v or less so in theory you could get an old computer PSU and use it for the power on the box....the advantages of using the PSU for the power would be A: you don't have to make a PSU for the thing B: you could use the other rails and connectors to power things like LEDs or fans or a coffee cup warmer or anything like that....it would also give you an on off switch (assuming you find a PSU with a switch....which is pretty common)

[hfcg]

All of this requires a constant use of power.
You could set up a selenoid to pull open a lock when all of the pieces are in the correct spot, thus using power only when you open the door.
I can not draw but the idea is that a lock is normaly closed, when the selenoid recives power the lock is pulled to open as long as there is power, Then goes back to locked when the power is cut.
These are way too expensive, but it is the general idea.

[dsenette]

All of this requires a constant use of power.
You could set up a solenoid to pull open a lock when all of the pieces are in the correct spot, thus using power only when you open the door.

i disagree....with either setup (yours or mine)...power would only be used when it's being applied to the solenoid by completing the circuit....if there's no power on the circuit then the solenoid would be "non energized" and therefore remain dormant...once you apply power (complete the circuit with the magnet switches)...then it will draw current....of course if you use a computer PSU it will draw power continuously as long as the power switch is in the on position (assuming you jumper it correctly to be always on so that you can use it as a bench supply)

[hfcg]

Well, now that you explained it in that way....
Is the desired result that the door will open mechanicaly?