This circuit doubles the frequency of an audio signal, thus changing its timbre. The circuit was found in an Elektor from the 90s. The components are common today.
This simple expandable circuit was obtained from a Popular Electronics from the 80's. The supply...
The frequency of the LC resonant circuit must be the same as that of the crystal and the JFET...
This circuit was obtained in a Popular Electronics of 1991. The magazine no longer exists, but the...