Searching \ for 'thermocople multiplexing' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: techref.massmind.org/techref/index.htm?key=thermocople+multiplexing
Search entire site for: 'thermocople multiplexing'.

Truncated match.
PICList Thread
'thermocople multiplexing'
1999\04\21@020126 by Romeo Dimitrov

flavicon
face
part 0 658 bytes
<BLOCKQUOTE TYPE=CITE><FONT SIZE=-1></FONT>&nbsp;<FONT SIZE=-1>&nbsp; Hi
all,</FONT>
<BR><FONT SIZE=-1>&nbsp;&nbsp;&nbsp; I am looking for simple ( low cost)
circuit to multiplex 4 (four) thermocouples</FONT>
<BR><FONT SIZE=-1>NiCr-Ni&nbsp; to one input amplifier.</FONT>
<BR><FONT SIZE=-1>Any tips or hints for the same would be helpful as well.</FONT
>
<BR><FONT SIZE=-1>Thanks in advance.</FONT>
<BR><FONT SIZE=-1>Romeo Dimitrov</FONT></BLOCKQUOTE>
&nbsp;
</BODY>
</HTML>

</x-html>

1999\04\21@120026 by Maris

picon face
At 07:58 AM 3/25/99 +0200, you wrote:
>      Hi all,
>    I am looking for simple ( low cost) circuit to multiplex 4 (four)
>thermocouples
>  to one input amplifier.
>Any tips or hints for the same would be helpful as well.
>Thanks in advance.
>Romeo Dimitrov
>

The lowest cost solution would be to use a CD4066 quad analog switch to do
the multiplexing - this would take 4 PIC pins to control. A more expensive
(and lower offset/leakage) addressable analog switch would only need 2 pins
for control. Check the Maxim and Linear Tech websites (http://www.maxim.com and
http://www.linear-tech.com) for their analog switches.

For the amplifier you need low input offset voltage and drift because of
the low microvolts/degC output from a thermocouple - I would suggest a
Linear Technology LTC1049 chopper-stabilized amp. This costs $4 in the
Digi-Key catalog (http://www.digikey.com). The LTC1049 datasheet shows an
application for a thermocouple amplifier; you can download this from the
LTC website.

The app note shows an LT1025A being used for cold junction compensation --
however, probably the simplest way to do this is to measure the temperature
of the board using a separate temp sensor IC and compensate in the
calculations. This would take an extra analog channel but might not need an
extra amplifier depending on the temp sensor output voltage.

Maris

1999\04\22@014150 by Romeo Dimitrov

flavicon
face
Maris wrote:

{Quote hidden}

 Hi , Maris
Thanks.
Is this combination is good - CD4051(+15V supply) , OP07(+15V , -15V) , LT1025.


Romeo

1999\04\22@115656 by Gary Crowell

flavicon
face
Siliconix app note TA201 describes muxing 4 thermocouples at:

http://www.siliconix.com/www/product/anmxapnt.htm



Romeo Dimitrov wrote:
{Quote hidden}

More... (looser matching)
- Last day of these posts
- In 1999 , 2000 only
- Today
- New search...