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Transformer for electro magnetic door lock?

Discussion in 'Electrics UK' started by coopersim, 25 Jan 2007.

  1. coopersim

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    I have an electro magnetic door lock, it is rated 24 volts 3 watts, can anyone advise of a suitable transformer to run this from?

    Thanks
     
  2. bernardgreen

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    First two questions ?

    Is it an AC ( alternating current ) or DC ( direct current ) lock ?

    Is it energised to lock ( fails to open on power failure ) or energised to release ( cannot be opened remotely during a power failure )
     
  3. coopersim

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    1. It's DC rated

    2. It's energsied to lock, so will release when power is removed
     
  4. bernardgreen

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    RS Components Stock No 310 2014 or 541 7560

    Battery backed 24 volt 24 volt 1 amp ( more than you need but means the unit is not stressed and expansion is possible )

    Other sources are available but for speed and convenience RS is worth the extra cost.
     
  5. coopersim

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    Thanks for the info - however I'm not bothered about the battery backup element - just a cheapy transformer !! I'll have a look on RS Spares though, thanks again.
     
  6. bernardgreen

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    It is NOT a transformer you need. You need a power supply with transformer and rectifier and smoothing capacitor. Without the capacitor the lock may buzz as the rectifier will be giving raw DC ( on-off 100 times a second ).
     
  7. coopersim

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    what about this one - 418-2443
    or this one - 347-7144 ??
     
  8. Steve

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    Dont they sell proper power kits for these locks? All the mag locks i've seen have a white box on the wall above the door, with power healthy, battery healthy lights.

    The box contains all the electronics for the system, and releases the door on closing an external contact (push to release switch or numeric keypad)
     
  9. bernardgreen

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    My only concern with switch mode power supplies is there is more to go wrong in them. And they can be a source of interference to nearby electronic equipment. Sometimes they have to have a minimum load and removing all load can cause them to lock up. The data for these two does not mention a minimum load requirement

    Sometimes the back EMF from a switched inductive load will trigger the over voltage protection. You will need a back EMF diode across the coil and maybe some additional suppression in the form of a capacitor on the output of the power module
     
  10. coopersim

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    This isn't as simple as I first thought! I'm prepared to spend about £30, what would you suggest in this instance? It is only for domestic installation, but there is sensitive electronic equipment in the area where it will be installed - namely a wireless ADSL router and a wireless alarm system
     
  11. bernardgreen

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    Nothing is as simple as it looks. As Crafty mentioned the makers of the lock may have something in their range.

    I will have a think and get back tomorrow.
     
  12. coopersim

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    I agree! However, there is no make on the lock, it is a simple lock that I bought from a local electronics shop with no box, the chap I spoke to suggested a 'laptop style' transformer, but I really want something that I know will be adequate.

    Any ideas would really help.
     
  13. breezer

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    any chance of a pic?

    or more info?

    is it really a mag lock?

    does it have2 parts or one?

    does it look like

    [​IMG]

    or

    [​IMG]
     
  14. coopersim

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  15. breezer

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    so its a white box with a red cross, not seen that one before
     

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