|Do you ever wish you could stop all the phones in your house from disturbing you?
Well you can....easily.The UK system of telephone wiring is different to many others because it uses three wires to interconnect the phones unlike the American system which only uses two. The third wire is the bell wire. This carries the ringing current between the sockets. At the Master socket there is a capacitor between the "B" wire on terminal 2 and the "Bell" wire on terminal 3.
By disconnecting this wire from the master socket it will stop the bells from ringing on all other phones in the house although the master socket will always ring. The circuit shown below will disconnect the bell wire to all the secondary sockets when the relay is operated.
The most simple method of operation is to operate the relay at night so that the phones don't ring in the middle of the night and wake you up. If you have an answering machine connected to the master socket it will take the calls without you being disturbed.
Taking this idea a step further, by connecting a Caller ID aware modem or similar PC interface device to the master socket, your Home Automation system can take control of the bells on your telephone line. You can now use the Caller ID information to control the ringing.
I cannot guarantee that this circuit will work with all telephones as some of them do not conform to the UK three wire wiring. Please dont ask me for software for the PC as this will be different for almost every user and I havent got this in use on my system. There are several software packages available on the net for Caller ID interfacing and if anyone has some good links I will add them to this project.
This page last updated : 11th October 2000