This 1969 Mullar circuit appears elsewhere on this site. The circuit uses germanium diodes and the indicator is microammeter with zero in the center of the scale.
This circuit is from a 1978 publication. It can be assembled with BC548 transistors for NPN and...
This double-T sine wave oscillator was found in the December 1995 issue of Electronics Now...
This powerful source was obtained in an American documentation of the 80s. Some components are...