I am starting a project to implement a "smart" lock for my door using Arduino nano, a solenoid deadbolt and a fingerprint reader. Which on its own works fine, but the whole project will run on a battery and I would require a "failsafe" method to unlock the solenoid deadbolt with a key. How can a solenoid deadbolt be controlled with a key without any current?


The normal way is to not use a solenoid to operate the deadbolt but to open the striker plate on the other side. This is called an electric strike

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That way you can use a conventional key operated bolt as a way to open the door when there is no electrical power.

You can buy these strikes for retrofitting to normal types of lock, both mortice locks and surface fitted locks.

  • Open the striker plate? I have no idea what that means :-) how can I control a normal deadbolt with an arduino then? :-) Jun 6 '17 at 9:11
  • @John, see above and consult a locksmith - these things are commonplace. I have one lying about somewhere but can't find it at the moment. You can easily control them using an Arduino and a relay shield. Jun 6 '17 at 9:14

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