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 ...

Here is an ideal Mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. Here is an ideal Mobile charger using 1.5 volt pen cells to charge mobile phone while traveling. It can ...

Here is a very simple telephone broadcaster or transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important ...

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 ...