| Undesired listening-in to telephone conversations may be prevented by the present circuit, which requires only two components to protect...
All items tagged with PDF and phone (6)
| It is sometimes necessary to make a telephone conversation audible to more than one person at either end or to make a tape recording of i...
| The proposed transmitter provides an optical(infra-red). that is, wireless, connection to a head-phone. The receiver is described in the nex...
| This article is one from our 90s collection, the articles are downloadable as a PDF for all our members. Although the information we have on...
| Rectifying the buzzer signal on a telephone line results in a voltage that may be used to switch one or more loads, for instance, a light...
| Telephones are now readily and cheaply available: two identical ones and a handful of components enable a simple house-telephone to be s...