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Astable multivibrator d.c. bell
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Audible signal apparatus
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Fire detector stabilizer circuit
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Code communication system
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Flip-flop driver for d.c. bell
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Ground detector system having fast response and decoupling of detector circuit
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Alarm latching circuit
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D.c. vibrating horn
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Condition detection and alarm system
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Programmed timing system
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Ground fault detector apparatus including a pair of complementarily connected bridge detector means for isolated electrical power systems
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Supervisory alarm systems
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Integrity check for fire alarm circuits
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Personnel information register system
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Selective suppression control of amplifiers in intercommunication systems
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Electronic audible alarm devices having plural oscillators
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Apparatus for detecting operating room electrical line ground faults
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System for setting secondary clocks
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Bell striker reciprocating motor
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Surge limiting system
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