If you are lucky enough to have a big house, a large garden, and small children, this project just might interest you. It’s actually a telephone ringer capable of making any mains-powered device work ...

Using modulated rectangular waves of different time periods, the circuit presented here produces ringing tones similar to those produced by a telephone. The circuit requires four astable ...

A simple yet effective circuit to generate a POTS-compatible ringing voltage can be made from National Semiconductor's LM4871 audio-amplifier IC and a dozen passive components (see the figure). This..