[aklug] Re: Making a temperature sensor

No luck on the 1-Wire pyranometer, however you can get a 1-Wire device
that has a 4-channel A/D converter with 16-bit resolution:

http://www.maxim-ic.com/products/1-wire/

Maxim bought Dallas Semiconductor a few years ago and continued the
1-Wire product line.

bob@estimations wrote:
> Thanks for the feedback, y'all. The DS18S20 1-wire digital device is
> most interesting -- especially seeing what you can do with owfs,
> owhttpd and rrdtool. Very cool!
>
> As far as finding an appropriate potting compound, a bit of research
> turned up http://www.epoxies.com/therm.htm. After discussing my
> application with sales, I ordered a sample of their 50-3151 FR
> product to test. Will report...
>
> Another question. In addition to temperature, I also want to measure
> solar radiation, and came across a $20 pyranometer kit available at
> http://mysite.verizon.net/brooksdr1/pyranometer/pyranometer.htm. It
> returns a 0-2.5V signal. Dr Brooks says it needs a minimum of 12-bit
> resolution. Until reading this feedback on other temperature
> measurement ideas, I had been looking at a labjack USB A/D converter.
> http://labjack.com/u3. But maybe this signal can also be measured
> with these 1-wire devices and owfs?
>
> Thanks,
>
> Bob
>
>
>> Date: Sat, 21 Nov 2009 16:14:39 -0900
>> From: Jim Courtney <courtney@ieee.org>
>> Subject: [aklug] Re: Making a temperature sensor
>>
>> You should look into the maxim-ic DS18S20 "1-wire" digital devices. They
>> are about the same size as the analog parts, and with linux you can get
>> up and running pretty fast. They have three leads, 5V, return, and data.
>> You can get a 1-wire bus master for USB or RS232, and daisy-chain dozens
>> of devices quite a distance away. Each has it's own unique address and
>> the software goes out and finds them all. I'm running owfs and owhttpd
>> to talk to the devices with a USB bus master. I use rrdtool to grab the
>> temperatures from the owfs (one-wire file system) periodically and make
>> graphs I can check out online. You can see them at 99645 dot com port
>> 3002 . For my only outside sensor I heat shrinked the whole thing and
>> left the top of the device exposed so it responds quickly. If you want
>> to pot the device, 2-part epoxy and empty shell casings should work. I
>> think they'll fit in a .22. The only downside I have found with these is
>> that they seem to bottom out at about -32F.
>>
>
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Received on Tue Nov 24 12:53:41 2009