This circuit monitors an old-style analog telephone line. We found it in the September 1991 issue of Radio Electronics magazine.
This circuit uses components that are still common despite being from 1995 documentation. The circuit can...
This circuit found in a 1964 US publication reverses the signal level by providing 9 to 0 V...
This is the typical circuit of an FET amplifier stage in the common source configuration. The circuit is...