How to make an alarm out of a doorbell?

Question

Do it yourself

There is a store, its front door opens silently and employees who are in the central part of the internal space often do not hear the regular visitors entering.
Task: to make a primitive alarm that will beep when the door is opened without wires through the entire store.
Idea: take an ordinary wireless door lock and remake it so that it reacts not to pressing a button, but to opening a sensor (preferably a battery-operated one).
I found advice on the forums to use the reed switch, but without details. I have practically no experience in soldering circuits, so I turn to experts: how can I solve this problem easier and cheaper?

Answer 1

Put a reed switch on the opening on the door jamb, and a permanent magnet on the door itself. You connect the reed switch instead of a button to a regular call.

Answer 2

I saw a special stray with a motion sensor - makes a "Ding" at the entrance.

Answer 3

a limit switch with a roller lever is suitable for reacting to an open door, you can connect a regular bell or a 220 V light bulb through it.

Answer 4

and you didn’t think that while the door is open, an alarm will occur (and if, for example, it needs to be opened for an hour? Or more? For example, in summer?). here a regular call is not enough. you need a slightly more complex circuit and it will be easier to take something ready-made for these purposes, because it will be difficult for you to assemble a circuit with a timer yourself. you can also do it all on an arduino - it will be a little easier (two arduins, both have a shield, for example, a zigbee or a regular radio, the same reed switch, for example, or a button with a roller, is connected to the first one, and a piezo emitter is connected to the second one (a tweeter is as nasty as computers sometimes put or in refrigerators