This tone recognizer circuit that relies on R5 and C1 was found in the December 1994 issue of Electronics Now. The circuit operates on voltages from 6 to 12 V typically.
Found in a Hands On Electronics from the 90s, this circuit can be easily assembled today, as the...
This 9 + 9 V symmetrical power supply was obtained in a 1977 symmetric publication but can still be...
This simple circuit for switching RF signals was found in an RF Design from the 90s. The circuit...