[aklug] Re: Making a temperature sensor

Ditto. I haven't wired mine up yet (I have 16 I need to put on a single wire)

On Sat, Nov 21, 2009 at 4:14 PM, Jim Courtney <courtney@ieee.org> wrote:
> 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.
>
> Bob at Estiminc wrote:
>> I'm interested in making up my own temperature=20
>> sensors using National Semiconductor LM34 IC's.=20
>> It looks like a transistor, a small can with=20
>> three wires coming out of it. Connect one wire to=20
>> ground, the 2nd to 5VDC and the third puts out a linear +10.0 mV/=B0F.
>>
>> spec sheet: http://www.national.com/mpf/LM/LM34.html#Overview
>>
>> My idea is to solder up the cable connections,=20
>> shrink some heat tube around each leg, slip it=20
>> all into a short length of 1/4" copper tube and=20
>> seal it all up with some sort of potting compound.
>>
>> I have a couple of questions. First of all, does=20
>> this sound like a good approach? Any better ideas? Hints? Tips? Tricks?
>>
>> Secondly, I'm looking for recommendations or=20
>> thoughts on a good potting compound -- something=20
>> thermally conductive but electrically insulating.=20
>> Is RTV silicon a suitable candidate?
>>
>> Bob Crosby
>>
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Received on Sat Nov 21 18:28:25 2009