When you design equipment that interfaces to a phone line, it is often desirable to be able to monitor the dc voltage on the line. This ability can be useful, for example, to determine whether a line ...

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 ...

When we make a telephone call in 2020 it is most likely to be made using a smartphone over a cellular or IP-based connection rather than a traditional instrument on a pair of copper wires to an ...

This article was originally published in March 2017 on the Residential Lighting website. Residential Lighting was the precursor to Furniture, Lighting & Decor. The magazine ran for 25 years and was a ...