Audio Amplifier with Logarithmic Digital Volume Control

The X9314 with the low voltage LM386 power amplifier is shown on figure below. 250mW of audio power will be produced by this circuit with only a 5V DC source. Plenty of sound for intercom, communications, or monitoring applications will be provided by this circuit.

It’s require a 74HC132 quad Schmidt NAND gate (U2) plus a few discrete¬† components to interface to U1, the X9314W 10Kohm XDCP. U2A output will be HIGH when either push-button switch, S1 or S2 is depressed. This immediately brings U2B output LOW which enables the XDCP. The astable multivibrator (U2C) will begin generating increment pulses after a short delay determined by R3 and C3. [Source: Intersil Application Note]