A-A-52525 Horns And Buzzers, Air-And Electrically-ActuatedThis CID covers horns and buzzers used in 12- or 24-volt (V) direct current (dc) circuits as warning signals in tactical vehicles, combat vehicles, and other equipment operating under severe and extreme conditions of shock, vibration, and climate.

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A-A-52525A

3.3 Performance requirements. Unless otherwise specified, horns and buzzers shall conform to all performance requirements of this CID at an ambient temperature of 25 + 8 degrees Celsius (°C).

3.3.1 Sound performance. Before determining conformance to the sound performance requirements, horns shall be mounted not less than 1.5 meters (m) from, and on the centerline with, the sound pick-up and shall be not less than 1.2 m from the floor and 3 m from any wall surface. Buzzers shall be suspended freely on a wire with the sound pick-up positioned not less than 102 millimeters (mm) from the face of, and on the centerline with, the buzzer. Ambient noise levels shall conform to SAE J377, paragraph 4.2.2.d, when all measurements are taken.

3.3.1.1 Sound intensity.

a. Horns. Horns shall conform to the sound intensity level, direct current, and airflow requirements of table I when operated at the nominal voltage, design voltage, and air pressure specified in table I. Type I horns shall produce sound within 5 decibels (A Weighted System Response [db(A)]) of the intensity level specified in table I when operated at air pressures of 415, 485, and 550 kilopascals (kPa) at the design voltage and nominal voltage.

b. Buzzers. Buzzers shall conform to the sound intensity level and direct current requirements of table I when operated at the design voltage and at a nominal voltage of 18 V dc for class 1 buzzers and 9 V dc for class 2 buzzers.

TABLE I. Sound performance requirements.

NOTES:

1/ Ampere (A)

2/ Cubic meters per second (m3/s)

3/ Horns and buzzers shall produce sound within 5 db(A) of this intensity level when operated at the nominal voltage.