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 Texas Instruments in a manual of operational amplifiers. Other...
Found in American documentation from the 1980s, this circuit shows how to use an LM3909 pulsator in a...
This circuit was found in an Elektor from the 90s. The integrated circuits are not very common...