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those darned NYC cyclists again
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October 22nd 18, 03:35 PM posted to rec.bicycles.tech
Ralph Barone[_4_]
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Posts: 853
those darned NYC cyclists again
wrote:
On Saturday, October 20, 2018 at 3:15:28 PM UTC-7, Jeff Liebermann wrote:
On Sat, 20 Oct 2018 13:39:27 -0700 (PDT),
wrote:
Running on body heat would give you sort of unlimited run time.
There are problems trying to utilize body heat. The worst is the lack
of an easy cold junction. In order to produce electricity, one needs
a temperature DIFFERENCE. If the body is the warm junction, where's
the cold junction? Simply heating something will work if you use a
thermocouple, but the efficiency is very low and little power will be
produced. For example, using the ambient air as a cold junction will
produce a fabulous 0.3 microwatts with this contrivance:
https://www.dailymail.co.uk/sciencetech/article-4368596/Incredible-powercell-converts-BODY-HEAT-electricity.html
There are other ways that seem to be better:
https://en.wikipedia.org/wiki/Energy_harvesting
--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Remember that you can use either junction as the cold one. You don't care
in what direction the current flows. All you need is a differential.
Using germanium you can get away with really low voltages.
The direction of the gradient isn't the issue. The absence of a gradient
(hey, everything inside my body is at body temperature!) is the problem.
Switching to a low band-gap semiconductor doesn't help.
I saw a news item once about a scheme to use sound waves to power implanted
electronics like pacemakers. I imagined the resulting headline - "He died
quietly."
Ralph Barone[_4_]
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