The circuit was designed to provide a monitoring scheme for a telephone line where several phones are installed, to indicate when one is being used. 4N25 – a general purpose optocoupler that consists ...

The circuit shown can detect when a shared telephone line is in use (see the figure). This is particularly useful when an automated device wishes to place an outgoing call without disturbing an... The ...

Here is a simple circuit to protect your Telephone, EPBAX, Telephone Modem etc from lightning discharge or line spikes. It uses a safety capacitor and Gas Tube Arrester to prevent damage of the ...

We started out with an old modem and ended up with a useful circuit to convert phone audio to regular line audio. This little hack is useful for those of us wanting to record Voip telephone calls for ...

THE best method of testing telephone circuits and apparatus is a problem to which a great deal of attention has been devoted of recent years. Speech is carried over a telephone circuit by means of ...

To any one who desires to acquire a good practical knowledge of the art of telephony we can recommend this book. In order to get the full benefit from it, however, he should first study a good ...