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Improvements in devices for acoustic signaling through the use of a continuous current source. (Machine-translation by Google Translate, not legally binding)
Improvements in devices for acoustic signaling through the use of a continuous current source. (Machine-translation by Google Translate, not legally binding)
Improvements in devices for acoustic signaling by using a direct current source, characterized in that said devices comprise an astable multivibrator and transistors that controls, by means of a relay, the change of tone of an acoustic warning means. (Machine-translation by Google Translate, not legally binding)
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