This circuit is from an old English publication from 1968. We can implement it with TIP32 transistors in a more modern version. Power can be done with either large batteries or a power supply.
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...
The operational amplifiers used in this circuit are old. The circuit is from documentation of the 70's, but...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...