Long range door knock sensor

My work space is 30+m away from my house.
Couriers have a really irritating habit of assuming the doorbell doesn't work so knock on the front door. There's no way I'll ever know about this.
I don't have and DON'T WANT an IOT doorbell / camera.

I'd like to build a sestem that can ring door bells both in a couple of places in the house and in my workspace. This would be triggered both by a conventional door bell and by someone knocking on the door.

A piezo sensor on the door can detect the knock, but I'm not sure the best way to differentiating between a knock at the door and vibrations from the letter box.
For reliability I'd like a fully wired system (not wifi etc) and my gut says that the output from an Arduino IO port isn't going to be up to powering a doorbell 30+m away.
Ideally, I'd like the whole thing running off a single power supply.

Any input would be greatfully received.

I would go low tech :

and place a door bell like this next to the post it

you can have multiple buttons and associate multiple ringers in different locations

it's radio but with quite a good range (I've a button at more than 60m at home) and battery life seems good (2 years since I installed it and still going)

My workshop is also a fair distance from my front door.

I have an real cheap intercom by the front door thats permanently on, so In my workshop I can hear the doorbell, whats going on in the house the burglars breaking the front door down etc.

I've got a RF doorbell, but sadly that doesn't take account of illetrate couriers. (Yes, I've tried taping a note to the door, but it wasn't reliable.)

I've thought about adapting an intercom, but it still doesn't really take account of the Anti-Doorbell Club.

Remove the door? :wink:

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Thanks for your contribution.

My own experience is that they don’t even knock - it’s faster to pretend no one was home and drop all the parcels at a collection point.
I witnessed that first hand a few weeks ago, the delivery truck came to my street stopped and departed without anyone stepping out nor calling.
A few minutes later I was getting a notification that a delivery attempt was made but I was not there and that my parcel was at the depot.
(I reported the issue).

So I’m not sure your knock detector will be useful.


If you still want to go that way, there are many secret knock detectors project available on the internet. Just drop the secret part and trigger a door bell (interfacing with a button is usually easy) . Some calibration might be necessary to avoid false detection if you feel vibrations from the letter box could trigger it too.

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