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 ...

This FM spy telephone circuit is mounted serrial with the phone line. When is signal on the wires this transmitter will radiate airwaves thru the wires wich act as anntenna. There is no need for ...

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 ...