Wireless doorbell with batteries
Wireless doorbell for an apartment : Wireless Doorbell With Batteries
Quote from Article entitled Wireless doorbell for an apartment:
Deciding to install a wireless doorbell in an apartment, you need to know, how one device differs from another one. Products vary depending on the principle of the power supply and are divided into the following types:operating off the supply line;operating off a self-contained power source.
Wireless bells, which are electrically powered, can be connected to the apartment wiring or operate off a socket. The first variant is properly called electromechanical. These products are almost not produced now; electronic devices came to replace them. The second variant presupposes a plug on a device, needed to be plugged into a socket for its operation.
The full version of the article can be found here.