This circuit for very low frequencies was found in an American documentation from the 90's. Transistors are for general use and the frequency depends on C1 and C2.
This circuit is from 1990 documentation. It can be implemented with BC548 transistors instead of...
When you speak into the microphone of this circuit, the sound produced in the speaker resembles a robot...
This circuit uses an operational amplifier that is no longer on the market but can be implemented with a...