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<div class="moz-cite-prefix">Phil,<br>
<br>
Thank you for your excellent comments. I am not an electronics
guy, so I will trust in what you say until others might find
issues to discuss.<br>
<br>
How can we proceed? You are in Nicaragua, right? <br>
<br>
As soon as I have some few units from Paul O., we can do some
trials.<br>
<br>
Paul<br>
<pre class="moz-signature" cols="72">Paul S. Anderson, PhD aka "Dr TLUD"
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a> Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
On 8/30/2012 9:13 AM, Phil Hughes wrote:<br>
</div>
<blockquote
cite="mid:CAAu-d+kZpFAumR3isDV7RJLx++Pf_seCFCUWoFtHxddx4bmOXg@mail.gmail.com"
type="cite">
<div>I see Paul Oliver's work to be excellent and appreciate how a
variable speed fan can offer excellent control over TLUD
operation. My reservation is that there are many places where
even the small power requirement (Paul says 1-2 watts) just
isn't available. Lots of people here in Nicaragua are totally
off-grid and don't have reasonable access to a way to charge a
battery. So, I am been thinking about options. Being, among
other things, an electronics geek, here is what I have been
thinking about.<br clear="all">
</div>
<div><br>
</div>
<div>Running the TLUD 8 hours a day at "average" fan speed means
12 watts per day. At 12 volts that's one ampere hour. I have
been thinking about a couple of approaches. One is "higher tech"
but may be a better solution at an equivalent or lower cost. In
both cases I am just thinking of a photovoltaic panel to charge
the battery. The difference is the battery voltage.</div>
<div><br>
</div>
<div>Small PV panels are pretty common on the surplus market. For
example, Electronic Gold Mine (<a moz-do-not-send="true"
href="http://www.goldmine-elec.com/">http://www.goldmine-elec.com/</a>)
offers an assortment. The specifications vary from 7 to 35 volts
open circuit with output power in the range of 1-3 watts. Prices
are from $4.50 to $15. As this is quantity one retail price
information, it is likely the could be found at significantly
lower costs.<br>
</div>
<div><br>
</div>
<div>As any PV-based system will need some sort of charge
controller for the battery and what PV cells (in particular,
what voltage) will be available at the best price point, I am
thinking that using a single-cell Lithium Ion battery (3.7 volts
nominal) would make the most sense. Units with a capacity of 2.2
ampere hours and more are commonly used in laptop computers.
They offer reasonable life, low cost and the possibility of
finding them on the surplus market. The cells can be paralleled
if higher capacity is needed.</div>
<div><br>
</div>
<div>A switching "up-converter" would be needed to supply the 12
volts needed for the fan. The speed control could be
incorporated into the up converter which would reduce the cost
and increase the efficiency. </div>
<div><br>
</div>
<div>The alternative would be to use a more or less 12 volt
battery (three Li-Ion cells in series) so that the up-converter
could be eliminated. My initial guess is that the reduced
electronics cost would not be as much as the increased battery
cost but it is a viable alternative as long as higher voltage
surplus PV panels are available.</div>
<div><br>
</div>
<div>While this sounds like a lot of electronics, this is all very
common stuff that you find in, for example, cellular phones.
There is some design work needed but the actual component costs
will be very low. </div>
<div><br>
</div>
<div>Comments? <br>
</div>
-- <br>
Phil Hughes <br>
<a moz-do-not-send="true" href="mailto:nicafyl@gmail.com">nicafyl@gmail.com</a><br>
<br>
<br>
<br>
<br>
<br>
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