Digital volume control

from an idea by R Conell 106 861digital volume control UP 91 R12 DOWN 3 17 VPP R17 12GNI/ IC1 EE July/August 1986 This digital potentiometer circuit is a hybrid analogue and digital design offering push-button controlled pro- grammable attenuation as well as high to low impedance conversion by means of a single active device. Digital noise is eliminated as effec- tively as possible through galvanic isolation of digital and analogue parts in the input attenuator. At the heart of the digital control sec- tion is a Type 2716 EPROM, which can be programmed either as shown in Table 1 or to individual re- quirements, as will be detailed below. At power-on, debouncer bistables Ni-N2 and N3-N4 force logic low levels onto EPROM address lines As and As respectively, selecting a programmed address range that supplies the digitally coded, initial volume settng. R-C network R16-C2 causes gates N7 and Ns to generate a clock pulse for IC2, which latches the 8-bit word from ICI, passes this infor...