AUDIO_AMPLIFIER_VOLUME_INDICATOR

Published:2009/7/9 5:12:00 Author:May | From:SeekIC

The indicator IS intended for use with an audio gmplifier or preamp⒒fter, but it can also be used in other applcations where a number of steps or changes must be counted rapidly.To prevent interferencewith the audio signal,the circuit is a static design．Thus,if the volume control is not adjusted,the circuit does nothint. The circuit does not need an external clock signal,because this IS derived from any changes h theleast significant bit (LSB).This is done by two differentiating networks:R9/C1 and RIO/C2,which double the frequencY of an available LSB signal. Moreover,to ensure that the counters of the indicator remain in step with the volume control,signals“up/down”and preset from the preamplifier are used．It might seem rather extravagant to couple the state of the counters in the prearnplifter with that the present counters,but it is a good way to keep the connections between the two units to a minimum,Furthermore,the present counters operate In 8-bit BCD，instead of 6-bit binary as used by those h the volume control (in the preamplifier).All that is required to display the state of the volume control are a couple of BCD-to-7-segment decoders and 7-segment displays. The preset h the indicator must be set h BCD code,Leading zeros are not suppressed so numbers up to and including 9 are displayed,startingwith a 0,The DIP switches and resistors RI through R8 In the diagram can be omitted if only one fixed preset is likely to be used.The resistors should be replaced by jump leads.



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