Controller for hidden compartment actuator

Discussion in 'The Projects Forum' started by GRNDPNDR, Jun 4, 2014.

  1. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    I'll try and keep this short and to the point. I have a "hidden" compartment that needs to be opened automatically using linear actuators.

    Because it's hidden it shouldn't be obvious how to open it. so there will be some sensors that will act as lockouts to the "open" switch so that unless the sensor input is correct the switch to open it would do nothing.

    The open switch itself should have some kind of security and be hidden itself. I was thinking something like a magnetic switch where you would place a magnet in a specific spot and if the sensors are in the correct position the compartment would pop open.

    As from an Arduino what kind of controller could be used to accomplish this? something more "professional/secure" than a simple microcontroller on a DIY board.
    What kind of switch could be used as the open/activate switch that could be concealed and not obvious how to use?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There was at least one fairly recent post almost the same app, a hidden door idea.
    Max,
     
  3. sirch2

    Well-Known Member

    Jan 21, 2013
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    Slightly off topic but one idea like this that I was told about which really satisfied my inner engineer was a steel plate set in a wall with bolts in the corners however if you removed the bolts you couldn't remove the plate. The trick was to put a grease gun down one of the bolt holes at the bottom of which was a grease nipple, pump some grease and it retracted a catch on the back of the plate and released the plate.
     
  4. John P

    AAC Fanatic!

    Oct 14, 2008
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    One disadvantage to the magnet idea is that the user must actually have a magnet. You could try with just a "magnetic personality" but I doubt if it would work.

    You could require the user to bridge between two contacts with his/her fingers (more fun if there are many contacts and you have to know which two to select--in a James Bond movie, of course, getting it wrong would deliver a fatal shock).

    Or you could have a hidden contact which would detect a touch via capacitance. That would be easy to trigger accidentally, but you could make the user tap out a little rhythm on the contact, or maybe operate several separate contacts in the right order.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    If this is in one of those "horseless carriages" that we never mention in this corner of the interwebs, be aware that it can get you in legal trouble. Just google hidden compartment arrests. An Ohio man was arrested just last Nov., and no drugs were found anywhere. The hidden compartment was the nail in his conviction writ.
     
  6. BobTPH

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    Jun 5, 2013
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  7. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Only if they're in your car :D
     
  8. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    All I'm really looking for is what kinds of controllers could be used.

    I actually found an article about Alfred Anaya and his contraptions, and for those types of systems it looks like relays were used.


    Back on topic though (and off that of cars) I'm just wondering about the actual controllers.

    I'm not doing anything with cars but this did get me thinking so I kind of just want to play around a bit. I've always wanted a hidden room in my house, but that will have to wait until I actually live in a house lol. In the meantime I can play around with ideas.

    There are small, inexpensive programmable relays are there not? that function similar to a PLC?
     
  9. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    How big/heavy is the door to this compartment and how much power do you think you'll need to shift it? Won't the power cable be a bit of a give away?
     
  10. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    as of yet I'm not sure. I'm waiting on some details. I had a buddy ask me for help on this since he isn't an electrical or electronics guy so that's why I posted here.

    This is why I'm just focusing on the controller aspect, as I understand he has a small compartment in his garage that's currently manual and he wanted it to be automatic.

    He has a hidden place where he stores stuff. It has a door that he wants to automatically open in a secret manner.

    That's about the extent of my knowledge on the matter.
     
  11. BobTPH

    Active Member

    Jun 5, 2013
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    A small solenoid should do it.

    Bob
     
  12. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    The opening and closing? yes, a solenoid probably would.

    But what control type of device could be used to control the activation of the solenoid so that it would only activate when it has input from X number of sensors, such as a pressure switch and 2 buttons.

    So you would need to stand in a specific spot and press two buttons before the system would release the solenoid.

    I'm sure it could be done with some relays, perhaps by using 3 relays and wiring their contacts in series so all 3 relays need to be closed before any power can get to the solenoid, but a controller or some kind of PLC like device may be better suited if I wanted to add some extra "security" like maybe having to press one of the buttons 3 times in a row or some weird thing.

    It's the concept that's got me interested and thinking of the different things to do with it, because it sounds kind of like automation which is what I went to school for.
     
  13. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Do you NOT want to use an Arduino (or Pic)?

    There are complete development boards for the latter to avoid the "microprocessor on a DIY board" look.

    The Arduino has everything you need professionally mounted. All you would need is to connect the sensors to the headers and write the controlling code.

    [​IMG]
     
  14. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    I'm not against an arduino, my concern is that it may be more prone to failure than relays, if there was a power surge for example and the arduino failed then it would need to be fixed before the compartment would be able to open again.

    maybe I'm over-thinking that?

    I'm also not very good with programming, but I guess it would be fairly simple to require that input must come from 3 "sensors" before it produces an output.
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
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    This would be the Smart Relay, they resemble a small PLC relabeled by a few manuf, such as Siemens, Idec, Square D, Omron etc.
    They can be programmed by the front buttons or for most the S/W is free.
    Apart from the normal I/O they have internal timers and counters and a real time calendar clock.
    Max.
     
  16. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Although relays are robust they are also current-hungry. Standard logic ICs would consume far less current and be able to combine the outputs of various switches/sensors to provide enable signals for actuator-driver FETs.
     
  17. sirch2

    Well-Known Member

    Jan 21, 2013
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    Any electro-mechanical system can fail, surely you are going to hide whatever control system you use somewhere other than the hidden compartment itself? That said, I suppose it would be a good idea to have a completely mechanical means of accessing the compartment. E.g. a key operated lock buried in the wall and completely covered over and you just keep a record of where to drill to find the key hole.
     
  18. inwo

    Well-Known Member

    Nov 7, 2013
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    I'm missing the "need" for any type of controller.:confused:

    Two or three hidden reed switches, pressure switches, or a combination, connected in series seems pretty secure.:)
     
  19. Alec_t

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    I agree with inwo. The more complex the system. the more likely it is to fail.
     
  20. GRNDPNDR

    Thread Starter Member

    Mar 1, 2012
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    I just can't really post too many details.

    Being current hungry isn't much of a problem, but I'm considering using IC reed relays instead of larger mechanical relays.

    I don't think I would need more than 2-3A for the actuators so as long as the contacts could handle that, a reed relay should work.
     
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