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Keyless and contactless Reset switch

Discussion in 'General Electronics Discussion' started by shakey1961, Mar 17, 2018.

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  1. shakey1961

    shakey1961

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    Apr 15, 2017
    Hi. I need / would like, to be able to momentarily interrupt a 12v line to reset a remote control / wireless switch.

    I have come up with the idea of using a NC reed switch then applying a magnet to disconnect it.

    It is going in a car and the reed / reset switch will be behind a plastic panel.

    Is this simple enough or is there anything else I should think of?

    I'm also looking for a keyring that is a magnet that I can touch on the panel to operate the reed switch.

    Any ideas?

    Many Thanks
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Reed switch + magnet sounds good, provided the magnet is strong enough to operate the reed switch behind the panel.
     
  3. Alec_t

    Alec_t

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    Jul 7, 2015
    ..... and provided the reed switch is able to handle making/breaking a high enough DC current when supplying a load which could be resistive/capacitive/inductive.
     
  4. shakey1961

    shakey1961

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    Apr 15, 2017
    It's supplying a remote wireless switch which in turn is feeding two small power supplies for two dash cams. I don't think's there's a lot of current involved
     
  5. ChosunOne

    ChosunOne

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    Jun 20, 2010
    Be aware that if you're going to carry a strong magnet on your person, you need to keep it well away from any credit-type cards that still use a magnetic strip---a magnet will scramble and render that magnet strip unreadable. Also, take care not to hold it against any wrist/pocket watch with mechanical movement.

    I use a concealed reed switch to trigger a garage door open/closed, and keep a magnet conveniently stuck out of sight on a piece of nearby steel. That way, it's always handy and those who know about it (members of the household) always have it handy. Consider keeping the magnet somewhere you can reach it easily from your seat.
     
  6. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Stolen.

    ak
     
    davenn likes this.
  7. ChosunOne

    ChosunOne

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    Jun 20, 2010
    ??
     
  8. shakey1961

    shakey1961

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    Apr 15, 2017
    Ta Dah.... I think I've found something better. A Hall Effect sensor operating a relay. In it's off state the relay is NC.

    Can anyone point me in the right direction for a 12v circuit version?

    Thanks
     
  9. AnalogKid

    AnalogKid

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    Jun 10, 2015
    I like it and I'm going to use it blatantly and shamelessly.

    ak
     
    ChosunOne likes this.
  10. KMoffett

    KMoffett

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    Jan 21, 2009
    It's a Trade Mark of the WTF LLC.

    Ken
     
  11. Bluejets

    Bluejets

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    Oct 5, 2014
    Most hall effect switches are open collector and will handle voltages well over 12v dc . Don't forget a small filter cap on the supply pins of the hall effect ( around 0.1uf if I remember correctly).

    Also note that there are many types of hall effect and you will be looking for one similar to an A1120 which will switch rail to rail.

    They can be operated by mounting the magnet on the back side of the ic and presenting a piece of steel to make the switch operate which may overcome some of the problems mentioned above. You will have to play with magnet strength to overcome the distance between ic and " key". If you use the rare earth magnets off Ebay you can stack them together. I have used 3 mm x 1mm for ignition systems.

    Stolen............ Good one
     
    Last edited: Mar 17, 2018
  12. ChosunOne

    ChosunOne

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    Jun 20, 2010
    Oh. Knock yourself out. :)
     
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