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AC/DC output

AC output

AC/DC output

Output signals are available at the AC/DC jack in the hardware interface panel at the base of the instrument (“Hardware interfaces” on page 6). Users are responsible for providing the cable to attach to this jack. For information about the pinout, see “AC/DC jack” on page 134.

AC output

The AC output is the amplified SPL of Meter 1. It is weighted depending on the "A, C, Z or F" selection for Meter 1. The maximum full-scale output voltage occurs near the upper dB level of the selected range and is approximately 3.16 volts "before clipping." The full usable range of this output is 60 dB. The relationship is shown in Table 8-1.

Relative dB

Output (Vrms)

Full scale

3.16

-10 dB

1.00

-20 dB

0.316

-30 dB

0.100

-40 dB

0.0316

-50 dB

0.0100

-60 dB

0.00316

Table 8-1: AC output

NOTE: The AC output signal is not intended to be used for testing instrument performance.

DC output

The DC output has a voltage range between 0 and 4.0 VDC that is produced by Meter 1 and includes the time response and frequency weighting settings for that meter. It represents and tracks the displayed dB level in one second increments. The DC output is linearly scaled over the range of –20 to 180 decibels. The highest level that can be represented on any selected range is always the ceiling of that range and depends upon the selected microphone model.

The DC output voltage level is related to the measured decibel value without regard to the range setting. You can calculate the SPL in decibels from the DC output voltage, VDC, by this equation:

SPL = 50 (VDC – 0.4) dB

Models SE and DL

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3M SE, DL user manual AC/DC output, AC output