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Thread: Automatic Lock/Unlock Using DC Motor

  1. #1 Automatic Lock/Unlock Using DC Motor 
    Forum Freshman
    Join Date
    Oct 2008
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    19
    I am currently working on a project to install a keypad on my door that will lock and unlock my door if the correct combination is typed into it. I have everything working except I am having problems getting the circuit to reverse the motor, which would unlock the door. I have been looking into using an H-Bridge but would like something more compact that will fit into the relatively small area of my door lock. Any ideas on how I could get the motor to unlock my door?

    ~HP


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  3. #2  
    Time Lord
    Join Date
    Apr 2008
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    5,328
    Could you use a solenoid (an electromagnet) or pair of them to kick a bolt one way or the other?

    EDIT: Simplest I think would be one solenoid that just pulls the bolt so long as you push a button. Let go and the bolt springs locked. It'll make a satisfying "thunk" sound too.


    A pong by any other name is still a pong. -williampinn
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  4. #3  
    Forum Sophomore
    Join Date
    Mar 2009
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    There are actually electronic door locks based on solenoids for sale. They cost about 25 dollars and you don't have to fool around with any motors that could potentially fail.

    The solenoid door locks go inside the wall part of the door, so when the door closes, the latch piece sticks in, just like a normal door. This way, you can also just use a key, normally. They are composed of a spring loaded latch, a solenoid, and a metal plate that stops the spring from opening when you haven't activated the solenoid.

    Alternatively, if you want to continue along the path you're using, you could get a servo motor that operates both directions.
    --
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  5. #4  
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    Apr 2007
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    An H-bridge wouldn't take up much space, especially if you used the IC kind.
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