This circuit was found in a 1971s English magazine. We can still assemble it using BC548 transistor. The other components are common. The supply voltage of 6 or 12 V depends only on the relay.
The circuit shown in the figure has a more efficient action, with an attenuation of 12 dB per...
This circuit was found in an American documentation from 1968. The circuit generates ladder-shaped...
We found this circuit in a 1967 documentation. The circuit can be designed based on current...