Re: Flashlight powered by body heat...

"jrwooden" <jim-TZ6VOGY/[email protected]> Fri, 05 Jul 2013 12:33:50 -0000
Newsgroups	gmane.culture.backpacking.light
Message-ID	<[email protected]>
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In watching the video it appeared it worked to some extent even at (what sh=
e claimed) was an "elevated" room temperature ... but clearly as ambient te=
mp. approaches 98F it's light output will trend to zero...=20

Of course if it's night time and close to 98F ... I'd consider it to be "le=
ss than ideal" camping weather  ;-)=20

Jim



--- In [email protected], "Eric Green" <eric@...> wrote:
>
>=20
>=20
> --- In [email protected], "jrwooden" <jim@> wrote:
> > Just stumbled across this ....
> >=20
> > No batteries, and should be pretty light weight....
> >=20
> > www.gizmag.com/body-heat-powered-flashlight/28113/
>=20
> Reading the details, it's useful only when it's cold outside, because it =
uses the temperature difference between body temperature and outside air te=
mperature to drive thermocouples. Same principle used for powering satellit=
es that are going beyond the limits of solar power, except the satellites u=
se a tiny piece of radioactive material to provide the "body heat".=20
>=20
> So a nice science fair experiment -- definitely should get the girl a sch=
olarship at a good college -- but not really practical for a flashlight tha=
t has to be usable at all outside temperatures including outside temperatur=
es that are below freezing (where you'd have to wear gloves to prevent fros=
tbite) or at body temperature (where it would not generate any power at all=
 due to no temperature difference).
>



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In watching the video it appeared it worked to some extent even at (what she claimed) was an &quot;elevated&quot; room temperature ... but clearly as ambient temp. approaches 98F it&#39;s light output will trend to zero... <br>
<br>
Of course if it&#39;s night time and close to 98F ... I&#39;d consider it to be &quot;less than ideal&quot; camping weather  ;-) <br>
<br>
Jim<br>
<br>
--- In <a href="mailto:BackpackingLight%40yahoogroups.com">[email protected]</a>, &quot;Eric Green&quot; &lt;eric@...&gt; wrote:<br>
&gt;<br>
&gt; <br>
&gt; <br>
&gt; --- In <a href="mailto:BackpackingLight%40yahoogroups.com">[email protected]</a>, &quot;jrwooden&quot; &lt;jim@&gt; wrote:<br>
&gt; &gt; Just stumbled across this ....<br>
&gt; &gt; <br>
&gt; &gt; No batteries, and should be pretty light weight....<br>
&gt; &gt; <br>
&gt; &gt; www.gizmag.com/body-heat-powered-flashlight/28113/<br>
&gt; <br>
&gt; Reading the details, it&#39;s useful only when it&#39;s cold outside, because it uses the temperature difference between body temperature and outside air temperature to drive thermocouples. Same principle used for powering satellites that are going beyond the limits of solar power, except the satellites use a tiny piece of radioactive material to provide the &quot;body heat&quot;. <br>
&gt; <br>
&gt; So a nice science fair experiment -- definitely should get the girl a scholarship at a good college -- but not really practical for a flashlight that has to be usable at all outside temperatures including outside temperatures that are below freezing (where you&#39;d have to wear gloves to prevent frostbite) or at body temperature (where it would not generate any power at all due to no temperature difference).<br>
&gt;<br>
<br>
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