In addition to tone control, this circuit of the SGS 1982 linear integrated circuit manual has a loudness control. The supply must be made with a 24V voltage source.
This 2-transistor circuit was found in the March 1958 Radio Electronics magazine. The coil...
Found in a Maxim documentation from the 1990s, this current-sensing amplifier uses components from the...
From an article in Radio Electronics magazine, May 1989, this circuit requires a dual power...