This circuit with two operating modes was found in the September 1989 issue of Radio Electronics magazine. Other operational amplifiers can be used. The power supply must be dual.
This vibrato circuit was found in Motorola's 1966 documentation. The circuit uses transistors of the...
Found in a magazine 73 for radio amateurs, in a 90's edition, this circuit uses a general-purpose FET...
This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even...