Digital Volume Control


This circuit could be used for replacing your manual volume control in a stereo amplifier. In this circuit, push-to-on switch SW1 controls the forward (volume increase) operation of both channels while a similar switch SW2 controls reverse (volume decrease) operation of both channels. A readily available IC from Dallas semiconductor, DS1669 is used here.

Circuit Diagram:

Circuit Diagram:


  • J1 = RCA Audio Input Socket
  • J2 = RCA Audio Input Socket
  • C1 = 0.1uF-16V Ceramic Disc Capacitor
  • C2 = 0.1uF-16V Ceramic Disc Capacitor
  • C3 = 0.1uF-16V Ceramic Disc Capacitor
  • IC1 = DS1669 (is available from Dallas SCo.
  • SW1 = Momentary Push Button Switch
  • SW1 = Momentary Push Button Switch


  • Replaces mechanical variable resistors.
  • Electronic interface provided for digital as well as manual control.
  • Wide differential input voltage range between 4.5 and 8 volts.
  • Wiper position is maintained in the absence of power.
  • Low-cost alternative to mechanical controls.
  • Applications include volume, tone, contrast, brightness, and dimmer control.
  • The circuit is extremely simple and compact requiring very few external components.
  • The power supply can vary from 4.5V to 8V.
  • The input signal should not fall below -0.2 volts.