This conventional 4 channel circuit with the 4017 and 555 was found in the November 1991 Radio Electronics magazine. The potentiometer can be 47k and it controls the speed of the effect.
This PA or Public Address amplifier with a few watts of power was found in the March 1986 Radio...
This circuit is from a Popular Electronics from the 90s. The circuit has a tone frequency...
This circuit is a telephone line simulator and can be used for internal communications. It is...