The operational amplifier for this tone control found in a 1977 Signetics manual may be the 741. The power supply must be symmetrical and the signal cables short. The bass gain is 20 dB.
November 2016 - Already available from Mouser Electronics on Texas Instruments' new DS280BR820...
This circuit generates a pulsed tone whose frequency depends on C2 and whose flashing depends on...
The presented circuit is suggested by National Semicondictor in its 1994 Linear Applications...