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

3.3.1.2 Sound quality.

a. Horns. Horns shall have a fundamental frequency between 100 and 500 Hertz (Hz) and the major noise-producing harmonic shall not be greater than 3500 Hz.

b. Buzzers. Buzzers shall have a fundamental frequency between 105 and 185 Hz.

3.3.2 Operating performance. Horns and buzzers shall be mounted as in intended use and shall be allowed to return to ambient air temperature after operation before determining conformance to the operating requirements.

3.3.2.1 Continuous operation. Horns and buzzers shall be continuously operated for 15 minutes and then shall meet the following requirements:

a. Horns. Horns shall conform to the sound performance requirements with a sound intensity deviation of not more than 5 db(A) of the intensity level specified in table I after continuous operation. Conformance to the sound intensity level at the nominal voltage is not required.

b. Buzzers. Buzzers shall conform to the sound performance requirements with no deviation from the sound intensity level specified in table I after continuous operation. Conformance to the sound intensity level at the nominal voltage is not required.

3.3.2.2 Intermittent operation. Horns and buzzers shall conform to the continuous operation requirements after 100 000 cycles of operation, where one cycle shall consist of 1 second "on" (energized) and 2 seconds "off".

3.3.3 Insulation resistance. The electrical insulation on the horns and buzzers shall evidence no cracking, charring, loosening, burning, smoking or other damage when a 500 volt root-meansquare (rms) voltage at a frequency of 60 Hz is applied. The voltage shall be applied for 1 minute between each terminal and ground, with the internal grounds disconnected.

3.3.4 Environmental performance.

3.3.4.1 Temperature. Horns and buzzers shall produce sound within 10 db(A) of the intensity level specified in table I when operated at the design voltage and air pressure under the following conditions:

a. The temperature of the ambient air and horn or buzzer shall be stabilized at 71°C.

b. The temperature of the ambient air and horn or buzzer shall be stabilized at -54°C.