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10
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ONSTRUCTION AND FUNCTIONING
Mechanical construction
Fig. 3 Calibrator mechanical construction (section).
Fig. 3 schematizes the HD 2020 calibrator structure (section). The battery compartment is on the right side of
the case. The printed circuits and the electronics are over and under the battery compartment. The display
and the keypad take up the higher part. The electro-acoustic transduction device is on the left and it consists
of a wide cavity with a piezoceramic generator and a feedback sensor. The device emits the signal through
the
½” microphone. An outer capillary hole balances the chamber static pressure protecting microphones
from overpressure due to their insertion.
Control electronics
Fig. 4 shows the calibrator block diagram.
Fig. 4 Electronics block diagram.
