Searching \ for '[EE]: K type Thermocouple Conditioner' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=type+thermocouple
Search entire site for: 'K type Thermocouple Conditioner'.

Exact match. Not showing close matches.
PICList Thread
'[EE]: K type Thermocouple Conditioner'
2002\05\08@184447 by Jeethu Rao

flavicon
face
Hi,
       I'm trying to interface a K type thermocouple to a 16f877. I tried using
       a 725 based Amp with a gain of around 200. But for some reason, the
accuracy
       is not very good. I think using a monolithic thermocouple conditioner would
be the
       best option. I downloaded the DS for AD595 and AD597. Both of which are
laser trimmed
       for K type thermocouples, with built in cold junction compensation giving a
steady
       10mV/C output (0.5C accuracy guaranteed). But unfortunately, they are not
available
       locally. Could you folks suggest any other commonly used Thermocouple
Conditioner ICs
       Or maybe point me to a discrete OPAMP based design.

Thanks,

Jeethu Rao

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


2002\05\08@203942 by Ashley Roll

flavicon
face
Hi Jeethu,

Someone on the list posted about a product from Maxim called the MAX6675 a
little while ago. It is a complete signal conditioner and ADC. It has an SPI
serial interface and 0.25 degC resolution. You simply terminate the
thermocouple leads to two of the pins and your done.

On the down side, I don't think it handles temperatures below 0 degC, but
this is not really a problem in most cases..

Next time I need to do a thermocouple input I'll be trying it.

I've got no idea about availability or price however.

Cheers,
Ash.

---
Ashley Roll
Digital Nemesis Pty Ltd
http://www.digitalnemesis.com
Mobile: +61 (0)417 705 718




> {Original Message removed}

2002\05\08@223331 by miked

flavicon
face
Yes the 6675(0-1023.75) and 6674(0-127.875) only go down to 0 C. There was a
delay in getting samples.

On 9 May 2002 at 10:40, Ashley Roll wrote:

{Quote hidden}

> > {Original Message removed}

2002\05\09@035025 by Alan B. Pearce

face picon face
>        Or maybe point me to a discrete OPAMP based design.

Check the national Semiconductor website for an application note on making
exactly what you are looking for.

You need AN225.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.


2002\05\10@021734 by Peter L. Peres

picon face
On Thu, 9 May 2002, Ashley Roll wrote:

>Hi Jeethu,
>
>Someone on the list posted about a product from Maxim called the MAX6675 a
>little while ago. It is a complete signal conditioner and ADC. It has an SPI
>serial interface and 0.25 degC resolution. You simply terminate the
>thermocouple leads to two of the pins and your done.
>
>On the down side, I don't think it handles temperatures below 0 degC, but
>this is not really a problem in most cases..

Thermocouples measure temperature difference, normally vs. ambient. So it
will handle 0C and below, down to temperatures where superconductivity may
appear in some of the materials used. Hint: you don't have to heat the hot
junction, you can cool the cold one.

The real problem is that al low differentials the output voltage can be
really really small (uV and less) and this brings some noise problems that
can be pretty bad.

Peter

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email spam_OUTlistservTakeThisOuTspammitvma.mit.edu with SET PICList DIGEST in the body


More... (looser matching)
- Last day of these posts
- In 2002 , 2003 only
- Today
- New search...