This circuit, with printed circuit board, is from an article in Radio Electronics magazine from May 1971. The circuit uses the C106 which was already a common component at the time.
This circuit for frequencies of 20 to 2 kHz was obtained in English documentation from 1966. The...
Indicated for adjustment in transmitters for the 11-meter band, this circuit with analog meter was...
The circuit shown uses the LM340 but applies to other regulators. We found this setting in...