General DSM8930 User Manual page 8

To display the maximum sound level measured since the
meter was powered on, press the MAX button. The text MAX
will replace MIN on the top line of the display and the digital
display will indicate the highest sound volume measured
since power on. While the digital display is showing the
maximum sound value, the meter continues to measure real-
time sound level inputs and to display its results on the
analog bar graph.
To exit MIN or MAX display mode and return the digital display
to showing real-time values, press whichever button
corresponds to the current display mode. You cannot switch
from MIN to MAX mode by pushing the "opposite" button. You
must first exit one mode before entering the other.
By default, the meter powers off automatically after
20 minutes of inactivity by the end user (no front-panel
buttons are pushed) to extend the "9V" battery's life. This
"APO" feature cannot be disabled. As a result, you cannot
track sound levels for longer than 20 minutes by feeding the
meter's 0 to 0.707VAC analog output signal from the jack on
the right side of the meter (Fig. 1, Callout E) into a chart
recorder. However, 20 minutes is more than sufficient to
perform and document a typical sound-level check.
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