Door bell installation for block of flats - indicates whether button pressed at main door or door to flat using different acoustic or optical signals

摘要

The door bell installation has a bell circuit supplied with a small alternating voltage and at least one bell which is activated by two bell-pushes located at different positions and giving two different sound signals, so that the positions of the bell-push can be recognised. A diode in series with the electrical contact of one of the two bell-pushes controls the emission of different signals depending on the difference in voltage supplied to it from the bell-pushes. USE/ADVANTAGE - Improved security, simple assembly.