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Reed switch

Discussion in 'General Electronics Discussion' started by Netrack, Sep 15, 2016.

  1. Netrack

    Netrack

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    Sep 15, 2016
    Hi and apologies but I am a complete noob. I am trying to build a circuit with some surface mounted reed switches (3-5) and a simple electric door lock powered by a small 12v battery. I have found a battery that is rated to 1.2 amps and the door lock draws 600ma but I cannot find any reed switches in the UK that I can use as they all seem to be rated for 500ma max. I was after the type with screw connectors rather than those that fit breadboards.

    The door lock can be found here https://www.amazon.co.uk/gp/aw/d/B0...ecure+bolt&dpPl=1&dpID=41EJ4YunO9L&ref=plSrch

    Any help would be greatly appreciated

    Thanks
     
  2. duke37

    duke37

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    Jan 9, 2011
    You should use a low power reed relay and use a transistor as a switch.
    The transistor should be capable of 1A and the base should be driven by a current of about 20 to 50mA.
    If you use a fet, the gate should be raised to 12V to turn it on and a resistor to earth to turn it off.
     
    Tha fios agaibh and hevans1944 like this.
  3. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Sir Netrack . . . . .

    1 Solution . . . .

    Solenoid Driver II.jpg

    73's de Edd
     
    Last edited: Sep 20, 2016
    Tha fios agaibh and duke37 like this.
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    That black wire labeled "-12 VDC" should be 0V, which is the negative pole of the +12 V source, shouldn't it? With only one 12 V battery there wil be no 112 V available, nor is it necessary.
     
    davenn likes this.
  5. Minder

    Minder

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    Apr 24, 2015
    The OP mentions SWitches, so they would either have to be NC type or OR'd N.O.
    Ones that have terminals are usually the window/door alarm system types and are N.C. all in series, (NAND'ed).
    M.
     
  6. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    :DI must declare that 73's de Edd makes the best and most colorful illustrations.
     
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  7. Externet

    Externet

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    Aug 24, 2009
    Not only colorful, but Edd invests time and effort to provide good pleasant responses to members.
    (-12) should be interpreted as the negative of 12V. A pull-off resistor at the base should be convenient to add.
    73 !
     
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  8. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    Yep . . . .only one 12 VDC supply involved, and those are referenced as being the two positive and negative terminals of same.

    ( Those two lines above were created immediately after Sir Haralds comment and have been carried forward in page cache memory of the laptop that they were composed upon. So I now enter that past neglected " Post Entry" and its info is now falling into place . . . 3 entry's later. )
     
  9. Minder

    Minder

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    Apr 24, 2015
    I always tend to use COM instead of GND to avoid the Earth confusion.
    We tend to lable the power e.g. 12DC+ 5vdc+ etc but neglegt the minus side..
    Often the commons are usually simple notation instead of the same practice as 12vcom, 5vCOm etc.
    M.
     
  10. Netrack

    Netrack

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    Sep 15, 2016
    Thanks for all the replies very much appreciated! As I mentioned I am a complete noob! What is the tip120 on the diagram and what does this do? I will no doubt have more questions but it might become clearer to me when I understand this bit of the circuit. I figured the switches would need to be NO. As this will be in a cabinet and the switches will need to be spaced apart (will draw something to explain) I guess I could use switches on bread boards but would need separate breadboards for each switch and connect with wires....
     
  11. Minder

    Minder

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    Apr 24, 2015
    Normally for ease/economy of wiring also fail safe, N.C. type are used, as in alarm systems I quoted.
    See ebay 321861539982
    M.
     
  12. 73's de Edd

    73's de Edd

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    Aug 21, 2015
    .

    Netrack. . . .

    Would it now be logical . . . to consider your other aspect, in the the operation of the solenoid.
    Of course that would be the simplest Neanderthalic crypto like consideration of the utilization of 1 through 3 reed switches for the activation of the solenoid.
    That would be the assignment of numbers one through nine to a " keypad " with that selective area being all cramped within the closeness of a hand span.
    Then some dope comes up and starts pressing any and all inclusive entry possibilities . . .for the rest of his life . .
    In hoping to crack the code of the opening of the lock .
    In reality the actual operation of the lock is dependent upon from 1 thru 3 series wired reed switches that are being physically located, CLOSE behind their select numbers to be activated by a neodymium magnets proximity of being placed above them.
    I max out at three, because I can only visualize the manipulating / positioning of three magnets at one time .

    73's de Edd
     
    Last edited: Sep 20, 2016
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