This is surely researchable on the web, but free time is a bit thin on the ground for me at the moment, so I thought I’d see what you all thought instead.
I have a basic no-frills lockable door knob on a basic no-frills wooden door. I want to change the mechanism to a proximity lock. That is, I want the door to be always locked unless I walk up to it with my keys in my pocket, in which case the door automatically unlocks.
Requirements:
It needs to be proximity activated but not extremely near-field. That is, I don’t want to have to remove a keyfob or card from my pocket and physically touch the unit with it. I want it to be “magic”. (Shifting my hip nearer the door is okay if the unit latches for a brief period.)
Weather resistant. The door is exterior, but protected from above.
Reasonably plug-and-play on a basic wooden door with a basic wooden door jam. If I needed to change out the entire door, I would do something else.
The lock doesn’t have to provide Fort Knox security. Just basic theft deterrence.
Is there a commercial unit out there that suits my needs?
I’m sure there is, but it is probably expensive and intended for commercial use. You probably need something that can operate an external deadbolt or something similar as opposed to something embedded in the door frame. I’m assuming you intend this to work from the outside so you can just push the door open once it unlocks. Usually there’s a motion sensor on the interior to unlock it anytime you come near by in that direction.
The result you’re looking for is a lot more complicated than the amount of work you seem to be prepared to do.
It can be done, but it requires a not insignificant amount of expense and equipment (electric strike, controller, power, etc.). I’ve not been in the locksmith industry for several years so I’m not fully up to date on all of the latest and greatest, but a simple one-device solution I do not believe is available at this time.