| 摘要 |
<p>Apparatus for controlling the volume of a speaker (42) includes timing means forming part of a microprocessor (20). The timing means includes first and second registers set to store first and second digital values respectively, counting means arranged to count sequentially and repetitively the values stored in said first and second registers, and output means (24) on which appears a signal having a repeating waveform comprising alternate first and second logic levels, said waveform being at said first logic level while the counting means is counting said first digital value and being at said second logic level while the counting means is counting said second digital value. Circuit means (26, 28, 40) connect said output means (24) to the speaker (42) whereby the volume of the speaker (42) is determined by the percentage of time for which said waveform is at said second logic level during a cycle of said waveform.</p> |
