Reverse engineering Motion detector sensor

Discussion in 'The Projects Forum' started by nxp, Nov 13, 2010.

  1. nxp

    Thread Starter New Member

    Jun 6, 2010
    7
    0
    Any one know how we can Reverse engineering this motions sensor.
    It's now powered with 120v. I want reduct it the powersupply to like 10v or 5v.

    The relay is powered by 24v, but i dont need it. All other part are 10v, 5v or 2v.

    Please can you explain shortly what is the function of same section of the board.
    [​IMG]

    [​IMG]

    [​IMG]


    It's hard to do?


    Thank you!
    David
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
    Hello,

    I think it will be hard to change the system as you do not know anything about the black blob on the green sideboard wich will do all the functions.

    Bertus
     
  3. nxp

    Thread Starter New Member

    Jun 6, 2010
    7
    0
    I'm sure the black chip is not working a 120v AC. I think the powersupply is done with only passive component, resistor, capacitor, it's possible? May be i can just bypass it?

    Maybe the best thing todo is to do a schema of the board on my computer?
     
  4. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    It's totally possible, but until you pull those power wires out of that extension cord and demonstrate that you're employing an isolation transformer, help ain't coming from here.
     
  5. nxp

    Thread Starter New Member

    Jun 6, 2010
    7
    0
    There is no transformer at all. The white wire is 120v+ and black ground. I can reverse it with no problem.

    Here the component merged (photoshop) with the circuit.
    [​IMG]
     
  6. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    What I'm saying is, you appear to have live mains connected to your board. That can complicate things very quickly in unfriendly terms.

    The fact that the board has no transformer on it should alert you to the potential of injury.

    I can make a simple suggestion to direct you in your quest, but not knowing your skill level, and having you engage a non isolated circuit, would be foolish for both of us.
     
  7. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    The OP should realize that a circuit with a direct connection to the line is always a lethal shock hazard. The particular circuit get approved because it is isolated in a plastic enclosure, so the actual circuit can't be touched, plus the usual warning about "no user-serviceable parts" label.

    The danger in this circuit is that any terminal can deliver a lethal shock. The layout is in an "any place it will fit" method, so finding points to measure the DC voltages is going to be interesting. I question if the risk is worth it?

    A search turns up almost 300,000 hits on "dc powered motion sensor". For example - http://avtech.com/Products/Monitor_-_Sensors/Motion.htm

    Note: I got ahead of myself in closing this thread. Thanks to the Wook for jogging my elbow.
     
    Last edited: Nov 13, 2010
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