<html><body bgcolor="#FFFFFF"><div><span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.226562); -webkit-composition-frame-color: rgba(77, 128, 180, 0.226562);"><br></span></div><div><br></div><div></div><blockquote type="cite"><div>
<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>
<div dir="ltr" align="left"><font color="#0000ff" size="2" 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></div></blockquote><div><br></div><div>Thanks Mikolaj! <span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">It was very tempting since this is just a tool for other fun and everytime I stop and make something, it slows down the origional experiment.</span></div><div><span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.292969); -webkit-composition-fill-color: rgba(175, 192, 227, 0.226562); -webkit-composition-frame-color: rgba(77, 128, 180, 0.226562);"><br></span></div><div><span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">However, it's way too expensive... I'm already over budget and I am pooooor :(</span></div><div><br></div><div>I'm also thinking that I can repurpose the freezer data logger supplies to an incubator (turn an old fashioned light bulb off and on (with some type of holding threshold to stop flickering) at 37 degrees C)) with a relay. </div><div><br></div><div>Thanks for the help everyone... </div><div><br></div><div><br></div><div>Cheers,</div><div><br></div><div><br></div><div>Glen </div><div><span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); "> </span></div><div><br></div><blockquote type="cite"><div>
<blockquote style="BORDER-LEFT: #0000ff 2px solid; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px" dir="ltr">
<div dir="ltr" lang="en-us" class="OutlookMessageHeader" align="left">
<hr tabindex="-1">
<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"><a href="http://www.maxim-ic.com/products/ibutton/ibuttons/thermochron.cfm">http://www.maxim-ic.com/products/ibutton/ibuttons/thermochron.cfm</a></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"><a href="mailto:leelist@lee.org">leelist@lee.org</a></a>></span>
wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">
<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"><a href="http://www.panasonic.com/industrial/includes/pdf/Panasonic_NiMH_Overview.pdf">http://www.panasonic.com/industrial/includes/pdf/Panasonic_NiMH_Overview.pdf</a></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"><a href="mailto:leelist@lee.org">leelist@lee.org</a></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"><a href="http://tinyurl.com/ydgvzgo">http://tinyurl.com/ydgvzgo</a></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"><a href="http://www.arduino.cc/playground/ComponentLib/Thermistor2">http://www.arduino.cc/playground/ComponentLib/Thermistor2</a></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"><a href="http://lee.org/blog/2008/07/10/vanson-8-aa-nicad-nimh-battery-charger/">http://lee.org/blog/2008/07/10/vanson-8-aa-nicad-nimh-battery-charger/</a></a><br>>
><br>> ><br>> ><br>> ><br>> ><br>>
><br>> >> -----Original Message-----<br>> >> From: <a href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net"><a href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net">noisebridge-discuss-bounces@lists.noisebridge.net</a></a><br>>
>> [mailto:<a href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net"><a href="mailto:noisebridge-discuss-bounces@lists.noisebridge.net">noisebridge-discuss-bounces@lists.noisebridge.net</a></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>> >>
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