coll circuit

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.
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

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.