This vibrato circuit was found in Motorola's 1966 documentation. The circuit uses transistors of the time that can be replaced with current common types. Power is done with 3 9V batteries.
This precision circuit, which also functions as a bridge, was found in a February 1967 Popular...
This circuit was found in a publication from the 90s. The circuit can be assembled with modern...
A first circuit that uses a phototransistor as a detector and is suitable for covering short...