This circuit is a simple digital volume control. The integrated circuit DS1669 is the one that increases or reduces the volume by means of two push buttons.
With this circuit we recompense the human ear deficiency to perceive less sharp and less deep tones of those that a melody really has at low volume.
We present you a retro assembly. This circuit was absolutely necessary years ago for us to listen to our vinyl discs. We all know what a preamplifier is, but what about R.I.A.A? R.I.A.A is a “Recording Industry Association of America”.
This circuit is made to protect the speakers from the "pump" inconvenience, that is produced in some amplifiers while they are on.
This simple circuit is based on the well-known integrated circuit LM3915.