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Bluetooth earphones are quite nifty and very popular. In terms of
convenience, if not sound quality, they're a big upgrade from
their wired predecessors. You can listen to the audio of your
choice without the wire catching on powerful machinery/door
handle.
Perhaps the biggest downside of
such products is the battery
life. Since everyone likes their earphones to be as light as
possible, they tend to be equipped with a piddly little 150mAh
lithium cell that might get you 8hrs playback, at least when new.
Charging them frequently requires any standard micro USB, but,
what if you don't have one handy? Sure you have one at home,
but if you're at home, you probably don't need bluetooth
earphones anyway! No, you're out and about, maybe on a 7hr
flight on a 757 owned by an airline that did not tick the USB box
on the last refit form. What do you have? Well, probably an
earphone outlet, in your phone, in the aircraft seat arm, in
someone else's phone, in the back of the hotel TV - lots of
places.
Now, standard specifications on earphone/line outputs aren't as
standard as they might be. This is because earphones themselves
are wildly variable. So anywhere from 8-600 Ohm impedance.
This means that at the low impedance, the amplifier must
maintain the relative modulated voltage at reasonably high
currents. Overall, there might be 0.4W available from a 1.7VRMS
output. Even better, you don't care about signal quality, and
things like aircraft probably have a lot of reserve power to
account for potentially hundreds of simultaneous listeners. So
you can probably cheat with a lower impedance circuit.
Next you need an opamp rectifier, tiny DC-DC regulator and
you're away. A 5V DC charging signal from the audio output of
anything.
[link]
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// an opamp rectifier, tiny DC-DC regulator and you're away. // |
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You don't even need that. You've got AC ... first, a small transformer to jack up the voltage, then a germanium full-wave rectifier, a capacitor, and a 78L05. |
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You could almost fit it all inside a fat 3.5mm jack plug. |
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[+] for the concept of harvesting "free" energy. |
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Apple, Samsung, and Google all have wireless Bluetooth
earbuds that fit in nifty little pocketable charging cases.
Airpods, Galaxy Buds, and Pixel Buds respectively. Might
consider giving them a look. |
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// A 5V DC charging signal from the audio output of anything// |
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What, I should put on high fidelity cans to charge these newly circuited earbuds? |
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//fit in nifty little pocketable charging cases.// |
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But the cases just have a slightly bigger lithium cell in
them. Kicking the can down the road if you ask me. |
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//I should put on high fidelity cans to charge these newly
circuited earbuds?// |
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No, this is the clever part, you could be wearing your
wireless earbuds while they're plugged in and charging. To
outsiders, you'll look like you're wearing conventional wired
earphones plugged into the audio out of an aircraft seat.
But, YOU will know they're REALLY wireless because you're
listening to the bluetooth audio of your phone. Although
admittedly your wireless earphones would still have an
actual wire, but YOU will know it's doing something
different. |
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I'm sure the boffins in R&D could even add functionality by
working out some kind of audio pass-through. If that works,
the marketing dept. will have a field-day selling the
lightweight battery-free model. |
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Great link. From that: "the vast majority of mobile phones do
not offer a standardized power and analog data interface. In
this paper we show
that it is possible to augment the ubiquitous headset jack with
exactly this functionality" |
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Apple removes headphone outlet. |
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//You might be 15 or 20 years late with this idea.// |
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I invented the turboprop in 1990, so at least the timing is
moving in the right direction. |
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The patent on the wheel's expired some time ago. If you can re-invent that and get a patent, you'll clean up. |
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Have Allison actually paid out anything to you for the turboprop yet ? |
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//Did you really bring some innovation to turboprop design?// |
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I was 8. I thought it was a natural progression of the turbojet-
turbofan line. So for that reason, propfans, turboprops,
geared turbofans, all derivative and not really patentable... |
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Of course not, because you'd be a minor, and your parents would have to co-sign the application. |
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