Digital Volume Control

Simple circuitry, Suitable for all kind of audio amplifiers

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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.

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Circuit Diagram:

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Parts:

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

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Notes:

• 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.

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