| US 7,501,935 B2 | ||
| Multi-frequency fire alarm sounder | ||
| Manley S. Keeler, Naperville, Ill. (US); Charles F. Fisler, Sycamore, Ill. (US); and Simon Ha, Aurora, Ill. (US) | ||
| Assigned to Honeywell International Inc., Morristown, N.J. (US) | ||
| Filed on Oct. 25, 2007, as Appl. No. 11/924,364. | ||
| Application 11/924364 is a continuation of application No. 11/008595, filed on Dec. 09, 2004, abandoned. | ||
| Prior Publication US 2008/0048841 A1, Feb. 28, 2008 | ||
| Int. Cl. G08B 3/00 (2006.01) | ||
| U.S. Cl. 340—384.7 [340/404.1] | 19 Claims |
| 1. An alarm indicating output device comprising:
an output transducer;
a digital source of a plurality of different driving frequencies coupled to the transducer, the source includes circuits to
sequentially and repetitively couple members of the plurality of different frequencies, one at a time to the transducer during
respective time intervals, and the source includes circuits to establish a respective duty cycle associated with each of the
frequencies, each duty cycle being less than 100% with some of the duty cycles different from others and with some of the
time intervals different from others.
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