If you’ve been to an apartment complex with a locked front door, you’ve seen the buzzer systems. You press the corresponding button for the apartment you want and can talk to the resident ...

The basic form of the circuit is built around a crosspoint switch array, with interfaces for each line and a Raspberry Pi to control it all. But that simple description doesn’t fully express its ...

Dual tone multi frequency (DTMF) is a technology used with touch tone phones, best known to users as the sound made when pressing a number key. It signals the phone company that you want to make a ...