Circuit Schematics for Telephone Applications

Are you asking for someone to physically build the circuit from the schematic? Whats the question?

Off hook line voltage is ~50v, on hook is ~2v, cut wire is ~0 but may be indeterminate. Let's say you want to detect the absence of >2v. That should be easy to build.

You should be able to use one of the pairs as a loop (i.e. short circuit the remote end of a pair) to hold a relay operated. Attach the contacts of the relay to an input of a commercially available alarm system, capable of dialling a phone number when the alarm is activated.

So... when the cable is cut, the alarm pair becomes open circuit and the relay releases. This trips the alarm, which in turn initiates the phone call.

Happy to elaborate further if required.

Cheers

Tony

If the phone line is cut, how do you make a phone call?

Obviously, you locate the alarm equipment on the "Network" end of a cable, not the remote location. A bit like not standing on the end of a tree branch, while you are sawing through it! :)

Tony

Do you want to change an electromechanical circuit diagram to a schematic diagram? If so, post the picture and see if you get any takers. If not, be clear about what you want.