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Date: Mon, 24 Feb 2014 22:29:29 +0100
From: schaefer <schaefer@iup.uni-heidelberg.de>
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Subject: Re: LF: RE: Lemon transmissions
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Hello Rik,

Yes, aluminium seems to be not a good choice. I've now stacked 3 lemon 
batteries and added 4x4700uF in parallel (unfortunately i cannot find 
the 10F gold cap that i thought i have here) but the voltage quickly 
drops to 15 mV (!) when i connect the PA :-(
Some more images:
https://dl.dropboxusercontent.com/u/19882028/MF/20140224_213046.jpg
https://dl.dropboxusercontent.com/u/19882028/MF/20140224_215944.jpg

I'm going to try Zn now. Hope to find some plates...

73, Stefan/DK7FC

Am 24.02.2014 21:48, schrieb Rik Strobbe:
> Hi Stefan,
>
> I am not sure that alumium is good for making lemmon batteries, as it oxidizes almost instantly. The thin oxide layer protects the metal from further oxidation (so you won't see any oxidation), but it might affect the standard potential.
> You can try Cu-Zn. That works fine a shold produce +/- 1V, so you will need some more lemmons ;-)
>
> 73, Rik  ON7YD - OR7T
>
> ________________________________________
> Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens schaefer [schaefer@iup.uni-heidelberg.de]
> Verzonden: maandag 24 februari 2014 21:03
> Aan: rsgb_lf_group@blacksheep.org
> Onderwerp: LF: Lemon transmissions
>
> Hi MF,
>
> I've bought some lemons and started to build a lemon battery. According
> to http://de.wikipedia.org/wiki/Elektrochemische_Spannungsreihe  (or
> english:
> http://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page) )
> i've decides to use aluminium and gold (pure, 999.9 :-) ) for the
> electrodes. But somehow the voltage is just 1.3 V for 2 elements in
> series. Actually it should be 6.4V! I have to check if there is maybe a
> short cut or so.
>
> This is the arrangement:
> https://dl.dropboxusercontent.com/u/19882028/MF/20140224_205538.jpg
>
> Later i will make some tests in WSPR-2 as DK7FC/L :-)
> If you have a receiver available that is "free", i would be happy for
> some WSPR reports.
>
> But first i want to improve the battery.
>
> 73, Stefan/DK7FC
>