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I need to put lighting down the side of moving rolling stock, along the lines of lighting found on planes and road trains. But the solution can’t use traditional power sources or solar as the wagons / rail cars interchange regularly and can be very long.

Lighting only needs to be active when the train is moving and needs to be powered ambiently, no power storage and no traditional power sources.

Could a piezo transducer power a reasonably bright LED for this? Is piezo the best option for train style vibrations? What would be required? How big would the overall unit need to be? Could one piezo transducer power multiple LED or a bright LED strip? That is, how many sensors would be required on a 40’ flatbed wagon to power say two bright LED lights or strips per side? What sort of life cycle timeframe could you expect to get out of the solution?

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  • \$\begingroup\$ Must they be continuously lit, or may they blink, using less bower? How smooth is the train -- welded, high-speed tracks, or bolted, with wooden ties? \$\endgroup\$ Commented Apr 1 at 23:01
  • \$\begingroup\$ Jam the brakes on hard at speed to create wheel flats for extra vibrations. \$\endgroup\$ Commented Apr 1 at 23:15
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    \$\begingroup\$ Wheel generators seem like the obvious solution that will just work without being fussy. Piezos are fun, but as a power source they have a lot of limitations. Put some magnets on a wheel or rotating axle and put a coil near them - rectify, perhaps a capacitor for smoothing. Might actually need current limiting, depending on the range of speeds the solution needs to work over. \$\endgroup\$ Commented Apr 2 at 0:29
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    \$\begingroup\$ Piezo harvester = uW. LED strip = W. You are about six orders of magnitude off. Could you harvest for many hours and store it in a battery/super capacitor and blink the LED very briefly? \$\endgroup\$ Commented Apr 2 at 11:35
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    \$\begingroup\$ What's the reason for ruling out solar here? Yes wagons get about, but why would that prevent solar on each wagon plus a small battery similar to no wiring solar garden lights? \$\endgroup\$ Commented Apr 2 at 15:37

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You'd have to do some experimentation for how and in what orientation (and perhaps what size, or range of motion) they might work best, but for something you could experiment with easily off the shelf, "shake flashlights" put a movable magnet in a coil of wire.

That's a dependable (if the train can shake them consistently - which is why I suggest wheel generators in a comment as more reliable, no matter how smooth the track) way to generate useful power at reasonable voltages, as opposed to high voltage at very low amps typical of piezos. I'm going to guess it's a lower cost solution, given additional complexity to convert piezo output, and the relative costs of piezo disks and magnets/coils.

Barring the case of a tailwind equal to the train's speed, a small turbine generator would be another possible approach to "movement = power."

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    \$\begingroup\$ A Savonius wind turbine like the design used in wind powered van vents could work well in this application due to the low height profile needed. \$\endgroup\$ Commented Apr 2 at 11:34

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