The circuit is from the 1977 National Semiconductor Audio Handbook. The bass and treble control is Baxandall type. The integrated circuit used is not common today.
We found this source with the CI 723, common at the time, in a 1989 paper. Power transistors must be...
Often, unauthorized people use the phone to make improper calls. A control for this is achieved with...
Found in an 80's documentation this circuit uses an integrated from the uncommon era today. Other...