Old phones with dials can be used in a simple home intercom system, as this circuit from Popular Electronics from the 90's shows.
This circuit, which can be used safely, has been obtained in a 1987 documentation. It consists of a...
We found this circuit in Electronics Now magazine from December 1995. Any operational amplifier can be...
PIC16F19197 Microcontroller Family Combines Battery-Friendly LCD Drive with Core Independent...