Found in a Popular Electronics from the 90s, it applies to the old answering machines that used tapes. It emits a warning beep on the drive.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...