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 circuit was suggested by Popular Elecronics from the 90's. The circuit has high input...
Figure 1 shows a circuit than can be used as time stage in timers, and other applications....
This circuit is from a Popular Electronics from 1993. The magazine is no longer printed, but the...