How i made my doors unlock... ON THE CHEAP (under $50) (electric strike)

So i had two major issues with the options we are currently given to automatically lock/unlock our doors.
they are:
1: cost (a replacement door handle with zigbee/zwave averages about $199, and a simple door deadbolt starts at $100.
2: The fact that all this stuff is for some reason required to be ran off of batteries. I’ve made some progress in my house migrating to arduino (also for cost) for this very reason. Incidently: arduino clone + smartthings shield = about $40 and arduino sensors are C.H.E.A.P. I have a bag of door switches i paid $1.00 apiece for.

Anyway, on to the implementation…

In advance, i will mention that everything that’s required to get this up and running was less than fifty dollars.
parts list:

  1. door striker, electric. Available on Ebay for as low as $21.99 at time of writing this.
  2. 12v power supply to run it with. 2amp models for led strip lights are under $5 on ebay.
  3. a lamp module. Also under $20.
    The system is pretty easy to install. Remove your old door striker plate and replace with the new one. You will probably have to enlarge the hole. The unit has two terminals you can attach the power supply to. It’s not polarized so it doesn’t matter which wire goes to which. Plug the power supply into the lamp module and you are done! (almost)

What you have to do in the IDE…

  1. create a new virtual device: a simulated lock.
  2. install the smart-app here
    Turn On/Off and/or Change Mode When Door Unlocks/Locks
  3. you’re good to go! when you toggle the virtual lock, the zwave module will turn the power on and off to the lock.

my implementation has the door unlock when someone comes home and lock again when the screen door closes.


Great idea and nice work here. Only thing that worries me would be telling my wife that she has to reach down and hit the button on the lamp module to manually unlock. Is that right?

Very nice!

I suspect the main reason more people don’t do this, is because of aesthetics. There isn’t always a place to plug the device into the wall right near the entry door and if there is, people still may not like the look of it.

Because I’m in a wheelchair, I know a lot of people who have electric strike plates and door openers, and usually the first discussion is aesthetics. :sunglasses:

The reason for this is really straightforward, and all the lock companies will say the same thing: what happens when the power’s out.

In many jurisdictions it is illegal to have a door which is default locked when the power is out. It’s just considered a fire safety issue. Which means if you go out to dinner, and the power goes out while you’re gone, with the electric strike plate operated from Mains power your door is then unlocked for anybody. That may not seem like a big deal, given the unlikeliness of the scenario, but it is the justification for battery use that the lot companies will admit to. (Although again I think aesthetics are a big part of it.)

You can see a note to exactly this point at the electric strike seller you linked to.

Using this method you could still unlock the door and operate the handle as usual, but if you don’t relock the handle the stike would be useless. Using a motion sensor you could set up a sort of request to exit function so that when there was motion during certain times of the day the strike would unlock.

A few concerns though.

  1. The zwave for locks is typically heavily encrypted making hacking it harder.

  2. In most cases you should use a fail secure strike. They are locked when power isn’t applied/unlocked only when power is applied. This way if your power is cut or goes out your door is still locked.

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These are against code on residential buildings in most US cities. Pretty major fine as it’s considered the same thing as locking a fire exit. You can usually use them on outbuildings.

Again, see the link the original poster had to the vendor for the electric strike that he used. They discuss exactly this issue.

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I would argue that with any building inspector provided that you can still unlock the door handle as the difference is pretty much nothing versus a dumb steel strike (which is always fail secure)

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I am however not suggesting you should knowingly violate a building code in your area. In my area they don’t have a code against it (that I know of) but it’s very unlikely that they do.

no. the door knob still works normally. You don’t ever have to unlock it with this setup but it still can be used that way. I have my module hidden across the room and very thin clear speaker wire running from the door to the power supply.

the model i purchased is fail secure and in fact when it is unlocked, the door still just doesn’t release. You have to release pressure from the striker plate completely by pushing the door tighter closed. then it swings open. But anyway as stated, if a power lock is the ONLY way you have of opening the door, i can see it being illegal. This setup is similar to a “buzz-in” setup. I’m actually considering implementing some kind of pattern press from my doorbell button if i get locked out. It’s also integrated with smartthings currently.

Code generally only requires fail safe devices if there is no mechanical means of egress that an untrained operator can use.

So, in this example, since there’s a knob or a lever on the door that you can simply turn and exit, it’s ok. Electric strikes are generally a lot simpler in this regard than other lock types like magnetic locks, which have a whole slew of additional needs.

All that being said, it’s not like building inspectors come walking through our houses regularly anyway, so you could probably get away with it either way!

It’s a clever idea for sure. I’d want to conceal wires and put the power supply elsewhere, but I also don’t have outlets near my doors anyway.

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Assuming the power comes in vertically you could later add a flushmount electrical cabinet and hang a picture over it. But that would probably bring your cost to high for the project to make sense.

The issue here is if it changes the behavior required to open the door in the dark during a fire.

If, as the original poster has described, the strike now requires that the door be pushed closed before it can be opened when the power is off, that likely fails the “untrained operator” test.

There are two ways to look at building codes. One is that it’s just some arbitrary bureaucratic nonsense that DIYers should ignore until they get caught.

The other is that code represents the knowledge and experience of a peer-reviewed group of experts who have seen cases where people died because they were unaware of necessary safety precautions in doing building projects.

The truth is likely somewhere in between, with some additional mix in from politicians overreacting or manufacturers trying to sell new product.

But the expert knowledge part is in there. It’s worth understanding why a particular code provision exists and what it’s trying to accomplish.

Because fire safety is a big deal for me (I’m a quad) I make sure that at my house, doors and light switches will work as expected even for a casual Visitor trying to escape a fire in the dark. I layer in technology on top of that, for example, Amazon echo is now our primary way of turning on lights. But I leave the basic mechanical panic mode stuff in place as well.

Everybody has their own priorities. :sunglasses:

I’m pretty sure that the reason this has to happen is most electric strikes have a safety feature that when there is pressure applied to them that even if power is applied the wont release. OP Can resolve this issue by adjusting the strike out a little bit so that there isn’t pressure on it. EDIT: I work in the commercial door industry so I forgot that the weather seals on his door are probably what is holding the door tight to the strike. Adding a closure device to the door may keep enough pressure off of the strike. end edit.

But that has nothing to do with the fact that any time he wants he can use the handle in a normal action retracting the latch(not the strike). Just as he would if there were a plain metal strike. It would be silly to fumble around with your phone trying to use power to unlock your door to get out. But you could probably set up a way to unlock your strike in the event that your smart smoke alarms go off.

i stated that the striker required a push to release. The doorknob still works normally. I do in fact have a smart smoke alarm but i wouldn’t trust the internet in that situation anyway, plus it’s not smartthings compatible. It’s a custom zigbee device that works only with Wink.

Cool idea John! I agree there was reasons for concern, but if I understand the device correctly, sounds like it should be setup like a standard apartment door, except the BUZZED in comes from the IDE via SmartThings? Anyone can easily walk OUT of the door, the handle works just fine as a normal door, they turn and release the latch assembly. But for anyone who wants to come INTO the building, they either 1. Need the key to turn latch assembly or 2. Can be BUZZED in which would disengage the striker, allowing the latch assembly to pull outwards? Seems feasible to me!


When you say you need to push to release it, if that is because there is pressure on the strike you should be able to fix it.

it’s evidently designed that way. I adjusted it to the point the door wasn’t sealed and it still needed to be done like that. I suspect it’s so the door doesn’t swing open on its own.

I like having the keypad on the outer side of the door. It gives me the flexibility to give the code to other users.

you could create a “man in the middle” arduino for just that purpose with a generic keypad.