| CPC F21V 33/0056 (2013.01) [F21V 23/04 (2013.01); H03H 11/04 (2013.01); H04R 1/028 (2013.01)] | 14 Claims |

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1. An audio filtering and power extraction apparatus for filtering out audio signal and extracting power from a combined signal and direct-current power line including both DC power and an electrical audio signal, comprising:
a. an input configured to functionally couple to a combined signal and direct-current power line;
b. a filtering extractor system functionally coupled to the input, including:
i. a DC sensing switch circuit; and
ii. a second order low-pass filter functionally coupled to the DC sensing switch circuit, the second order low-pass filter including:
1. An inductor or virtual inductor in combination with
2. a capacitor and resistor in series with each other; and
c. an output functionally coupled to an output of the filtering extractor system and through which output extracted power is provided.
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