Looking for a Patio door lock which will maintain last position, regardless of power


I found a link to another post:

but it is not quite what I want. I have a “hut” which has power intermittently, and it only has one way to enter, thru a sliding patio door. This door has a manual lever lock on the inside. What I am looking for is the following:

  1. when someone is inside and there is no power, the user inside can still open and close the door and use the manual lever lock
  2. when someone is inside and there is power, the user inside can still open and close the door and use the manual lever lock
  3. Someone from the outside can use a keypad and “lock” the door, if there is power
  4. Someone from the outside can use a keypad and “unlock” the door, if there is power

I looked at the “drop bolt” solutions but they either open when there is no power or close when there is no power. I thought about using a linear actuator with a one inch stroke and a plate, similar to the door manufacturer ones that you can step on. The advantage of an actuator is if you apply +12V it extends and if you apply -12V it retracts. no power is needed to maintain the position.

But the actuators are typically built to “lift” and are overkill for this application, and are expensive by the time you get brackets form them and a DPDT relay They are around $80 CAD. (I’ve been looking for 3 days on the internet). Atypical one is here:

I looked at solenoids, but they are spring controlled and require constant power to maintain one of the positions

Has anyone done anything similar with something else? or found a cheaper($20) actuator? The absolute cheapest actuator I can find is $34US ($45 CDN) with no brackets or relay. The other issue is actuators have a high current draw around 750mA to 1A, which means the typical “find around the house which is no longer used” 120V to 12V adapter will not work. You have to buy a pricier one, around $12-15. It just seems like an overkill solution to use an actuator, as the actuator’s purpose is to lift heavy things, not act as a bolt



How often is it without power and for how long? Would a battery backup be enough to maintain the state until the power comes back?


How much force does the actuator have to provide? Some patio doors require quite a bit of force to lock. ( for comparison, the typical toilet flush lever is usually right around 5 pounds of force, but many door latches require 15 pounds of force to shift from locked to unlocked. .)

I dont want to risk that in case there is a fire in the night, as there is a bed in it. This is the only exit

I would also prefer something that does not require constant power. The hut is not used that often. There is no point in having a constant power draw if it can be avoided

The actuator would be at the floor similar to manufacturer step down bolts.

The force required would only be to overcome gravity. The more important force to prevent is lateral force.

essentially replacing the bolt from this picture:

with an electrically controlled actuator

I see. I am a wheelchair user, so I haven’t really looked into that device class at all for my own house.

There’s a good thread here on using actuators with smartthings that might be of interest. You would need to buy a much smaller actuator than the ones they are talking about, but those are available, usually under the search term “micro actuator.“

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Thanks for the link, hooking up of the actuator (if I find no other solution) as described in the link, would be the next step once I have one.

I think I’m going to pull the plug and get the $32 actuator, and try it. One other problem with the cheap actuator is there is no means to stop it if it encounters an obstacle. the chicken coop in the link you sent does this by monitoring the current. A good idea I must say. I think I may go for a mechanical approach, and that is put it on a spring. i.e. if it encounters an obstacle, the actuator would “move” compressing a spring. And once the obstacle is gone, it would spring back

Unless anyone has some ideas other than an actuator?!!

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