This harmonic oscillator controlled by crystal was found in an American documentation of the 90's. The circuit uses transistors of the time. Current equivalents can be used.
This sophisticated sinusoidal audio signal generator uses a Wien bridge configuration with an...
This AC amplifier using the 741 operational amplifier uses a dual supply from 5 to 12 V. The input...
This circuit was found in the Spanish magazine No longer in existence, Mundo Electrónico, in a...