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re: chest refrigerator article
22 jul 2005
scott willing wrote:
>fyi backwoods solar electric has been advocating this concept and
>selling an external thermostat to do it with for years.
http://backwoodssolar.com/catalogpages2/refriger2.htm
>item r-4e047, just under the crossley freezer.
i wonder who makes it.
tom chalko says the 2 aaa batteries onwould last "several months."
they might last longer (the shelf life date of duracell aaa's for
sale today is 2011) if they were trickle-charged... 3 months is about
2000 hours, and the aaa low-current capacity is about 1 ah, so they
might last till 2011 if trickle-charged at 1 ma via a simple charge pump
with a 0.047 uf cap in series with a 3.6 v zener diode to ground...
like this:
0.047 uf
-------||--------->|----
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240 vac - 3.6 v --- 3 v
50 hz ^ -
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------------------------
1 ma = 50c2x240 makes c = 0.04 x 10^-6.
the zener vs plain diode would avoid harming the load
if the battery is removed with the power on.
nick
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