Battery-powered device having a battery and loud sound detector using passive sensing

1. A device contained in a housing sized to fit into a battery compartment, the device comprising:

a processing circuit having at least two modes including at least a sleep mode and an awake mode; and

a passive sensor, powered by audio signals impinging on the passive sensor, that provides a mode signal to the processing circuit so as to cause the processing circuit to switch from the sleep mode to the awake mode, the passive sensor being in proximity to an alarm sound generator when contained in the battery compartment, the proximity being such that power sufficient to generate the mode signal from the passive sensor is provided by sound waves produced by the alarm sound generator.

2. The device of claim 1 , wherein the housing is sized to fit into a 9 volt battery compartment.

3. The device of claim 1 , wherein the battery compartment is a battery compartment of a smoke detector.

4. A method of sensing and communicating an alarm condition, the method comprising:

having a sound sensor placed in proximity to an alarm sound generator by placing the sound sensor within the battery compartment of an alarm device having the alarm sound generator, wherein the proximity is such that power needed to trigger a mode signal from the sound sensor is provided by sound waves produced by the alarm sound generator;

triggering a processing circuit to switch from a sleep mode to an awake mode in response to the mode signal from the sound sensor; and

initiating a wireless communication to send a message as to whether an alarm has been triggered, when the mode signal from the sound sensor is triggered.

5. The method of claim 4 , further comprising enclosing the sound sensor, the processing circuit, a wireless communication circuit, and a battery into a housing sized to fit into a battery compartment of the alarm device having the alarm sound generator.

6. The method of claim 5 , wherein the alarm sound generator is part of a smoke detector, and wherein the smoke detector is powered by the battery in the housing.

7. A device comprising:

a housing adapted to fit within a battery compartment of an alarm device;

a processing circuit having at least two modes, the two modes including at least a sleep mode and an awake mode; and

a passive sensor contained within the housing, powered by audio signals from an alarm sound generator impinging on the passive sensor, adapted to provide a mode signal to the processing circuit so as to cause the processing circuit to switch from the sleep mode to the awake mode, wherein the alarm sound generator is contained in the alarm device, the battery compartment of the alarm device within proximity of the alarm generator to allow the audio signals impinging on the passive sensor to provide sufficient power to provide the mode signal.

8. The device of claim 7 , wherein the housing contains the processing circuit.

9. The device of claim 7 , further comprising:

a communications module electronically coupled to the processing circuit and adapted to wirelessly transmit electronic signals.

10. The device of claim 9 , wherein the housing at least partially contains the communications module.

11. The device of claim 9 , wherein the processing circuit is adapted to cause the communications module to transmit a message indicating an alarm condition.

12. The device of claim 11 , wherein the processing circuit is adapted to cause the communications module to transmit the message in response to a determination that the audio signals impinging on the passive sensor correspond to an authentic alarm condition.

13. The device of claim 7 , wherein the mode signal is provided to the processing circuit without supplemental electrical power.