This 1 kHz circuit was found in American documentation from the 90s. The original operational amplifier consists of a double 741 at the time. The power supply must be symmetrical.
This circuit for conventional lines was obtained in a 1996 documentation. The circuit uses common...
This tube circuit was found in the magazine 73 for radio amateurs in an issue from the 1980s. Note...
September 2016 - can already be found at Mouser Electronics new integrated circuit from Texas...