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<DIV dir=ltr align=left><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=765235107-11042010>></SPAN>If you're just logging, and have $40 to
spend on a solution, look at the DalSemi^WMaxim thermochron
iButton:</FONT></FONT></FONT></DIV>
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face=Arial></FONT> </DIV>
<DIV dir=ltr align=left><SPAN class=765235107-11042010><FONT color=#0000ff
size=2 face=Arial>Where's the fun in that? ;-)</FONT></SPAN></DIV>
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size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><FONT color=#0000ff size=2
face=Arial></FONT> </DIV><FONT color=#0000ff size=2 face=Arial></FONT><FONT
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<FONT size=2 face=Tahoma><B>From:</B> Mikolaj Habryn [mailto:dichro@rcpt.to]
<BR><B>Sent:</B> Sunday, April 11, 2010 12:30 AM<BR><B>To:</B> Lee
Sonko<BR><B>Cc:</B> Glen Jarvis; Noisebridge Discussion
List<BR><B>Subject:</B> Re: [Noisebridge-discuss] Termperature sensor
datalogger<BR></FONT><BR></DIV>
<DIV></DIV>Do you need realtime data or just logging? If you're just logging,
and have $40 to spend on a solution, look at the DalSemi^WMaxim thermochron
iButton: <A
href="http://www.maxim-ic.com/products/ibutton/ibuttons/thermochron.cfm">http://www.maxim-ic.com/products/ibutton/ibuttons/thermochron.cfm</A>
<DIV><BR></DIV>
<DIV>m.<BR><BR>
<DIV class=gmail_quote>On Sat, Apr 10, 2010 at 11:34 PM, Lee Sonko <SPAN
dir=ltr><<A href="mailto:leelist@lee.org">leelist@lee.org</A>></SPAN>
wrote:<BR>
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<DIV class=im>> This is excellent. Thank you for the help.
I don't mind<BR>> recharging batteries often - but will they operate
properly<BR>> for a day, explode, cause aliens to visit my home,
or<BR>> anything else weird?<BR><BR></DIV>The batteries won't explode or
anything dreadful. I'm pretty sure they'll<BR>deliver a low voltage and wear
out quickly. I'll hazard a wild guess and say<BR>you'll get 60% of what
would be a full charge out of them. You could<BR>compensate by using more
batteries in series and recharging more often.<BR><BR>You want a very stable
voltage source for the thermister's voltage divider<BR>so you should go
through the onboard regulator and be sure to have more than<BR>6.0 volts of
batteries.<BR><BR>The Arduino draws about 40ma.. maybe another 10ma for the
thermistor. It<BR>would normally run for about 20 days on 1,000ma of
batteries. Maybe you'll<BR>get 12 days of battery at low
temperature.<BR><BR>I found this datasheet<BR><A
href="http://www.panasonic.com/industrial/includes/pdf/Panasonic_NiMH_Overview.pdf"
target=_blank>http://www.panasonic.com/industrial/includes/pdf/Panasonic_NiMH_Overview.pdf</A><BR>page
10 shows the batteries having low voltage (maybe 0.1 volts low) and
80%<BR>of normal temperature capacity at -10 degrees celcius. That's a good
sign<BR>for you I think :-)<BR>
<DIV>
<DIV></DIV>
<DIV class=h5><BR><BR><BR><BR><BR><BR>><BR>> I don't
mind experimenting, but if I get battery acid in<BR>> the freezer, I'll
be in Trouble! (with a capital T). I<BR>> already have petri dishes of
genetically engineered e. coli<BR>> in the refrigerator, and am about to
put small frozen viles<BR>> in the freezer... oi! :)<BR>><BR>>
Glen<BR>><BR>> On Apr 10, 2010, at 8:54 PM, "Lee Sonko" <<A
href="mailto:leelist@lee.org">leelist@lee.org</A>> wrote:<BR>><BR>>
> A thermister is probably what you want.<BR>> ><BR>> > maybe
Jameco product 207037<BR>> > <A href="http://tinyurl.com/ydgvzgo"
target=_blank>http://tinyurl.com/ydgvzgo</A><BR>> ><BR>> > The
resistance changes according to a curve so it needs to<BR>> be
massaged<BR>> > a little. This should do it for you.<BR>> > <A
href="http://www.arduino.cc/playground/ComponentLib/Thermistor2"
target=_blank>http://www.arduino.cc/playground/ComponentLib/Thermistor2</A><BR>>
><BR>> > If I remember correctly, it's accurate to about +-0.2
degrees.<BR>> ><BR>> ><BR>> > For the batteries at subzero
temperatures... ugh. Buy extra<BR>> batteries?<BR>> > This cheap
charger works great:<BR>> ><BR>> <A
href="http://lee.org/blog/2008/07/10/vanson-8-aa-nicad-nimh-battery-charger/"
target=_blank>http://lee.org/blog/2008/07/10/vanson-8-aa-nicad-nimh-battery-charger/</A><BR>>
><BR>> ><BR>> ><BR>> ><BR>> ><BR>>
><BR>> >> -----Original Message-----<BR>> >> From: <A
href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net">noisebridge-discuss-bounces@lists.noisebridge.net</A><BR>>
>> [mailto:<A
href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net">noisebridge-discuss-bounces@lists.noisebridge.net</A>]<BR>>
On Behalf<BR>> >> Of Glen Jarvis<BR>> >> Sent: Saturday,
April 10, 2010 7:40 PM<BR>> >> To: Noisebridge Discussion
List<BR>> >> Subject: [Noisebridge-discuss] Termperature sensor
datalogger<BR>> >><BR>> >> I am doing a diy bio experiment
on survival rate of e. Coli after<BR>> >> freezing (with different
cryo agents). I'd like to make a quick<BR>> >> arduino data
logger.<BR>> >><BR>> >> I need to measure temperatures
around -20 degrees C (about<BR>> -4 degrees<BR>> >> F.)<BR>>
>><BR>> >> I did something like this with my Lego mindstoms
sometime<BR>> back - but<BR>> >> it was for a very short amount
of time.<BR>> >><BR>> >> I need to take regular
measurements (like once every 15 min) for a<BR>> >> month.<BR>>
>><BR>> >> Does anyone know a good vendor for a temperature
sensor in this<BR>> >> range?<BR>> >> What are the issues
I may encounter operating a battery in<BR>> sub zero<BR>> >>
freezing temperatures on an ongoing basis? I don't mind<BR>> changing
out<BR>> >> batteries or retrieving device for data retrieval once
per day.<BR>> >><BR>> >><BR>> >> Glen<BR>>
>> _______________________________________________<BR>> >>
Noisebridge-discuss mailing list<BR>> >> <A
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href="https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss"
target=_blank>https://www.noisebridge.net/mailman/listinfo/noisebridge-discuss</A><BR>>
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