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General Category => Analog discussion => Topic started by: tpone on March 02, 2008, 11:00:50 AM

Title: Analog temperature measurement
Post by: tpone on March 02, 2008, 11:00:50 AM
I happen to have a temperature sensor for temperatures up to 600 degrees C. But this sensor is not for connecting it to a pic. I measure the resistance and i figured that it changes on the temperature change.

How can i display the temperature on an lcd? What can i use?
Title: Re: Analog temperature measurement
Post by: kostas on March 02, 2008, 13:22:10 PM
Use an A2D converter
Title: Re: Analog temperature measurement
Post by: kam on March 02, 2008, 15:07:23 PM
or use the PIC 16f88 that has built in a2d and can be directly connected to your display! neat!
Title: Re: Analog temperature measurement
Post by: ScubaCap on March 02, 2008, 16:17:18 PM
Actully, all these sensor happen to have an output of 0-10 or 4-10 or 4-20 or something like this, that means 0 to 10 mA scale or 4 to 20 mA scale or 0 to 10 volts scale.

If you can find some more info you can have the exact result you want. If for example this is a linear probe for temperatures 0 to 600 degrees with output 4-20mAmperes, means that with 24Vdc (or 12 or whatever it needs) it will sent 4mA when 0 degrees and 20 mA when 600 degrees. This you must figure out.
Title: Re: Analog temperature measurement
Post by: tpone on March 02, 2008, 16:31:59 PM
I have no specification for this. is there a way to find out what the hell is it?
Title: Re: Analog temperature measurement
Post by: kam on March 02, 2008, 22:56:56 PM
With the ancient method of try and error.
Make some tens of measurements for different temperatures
Title: Re: Analog temperature measurement
Post by: ScubaCap on March 03, 2008, 01:06:41 AM
and you have a long way in front of you! Better leave this all day with an ohmmeter or an ammeter (better) and some 24V or 12V supply, and have a simple thermometer. Every 30minutes or every hour mark the temperature and the amperage. This will give you some results.

In worst case, if you do not find anything with these results,post them here and maybe we can help you.
Title: Re: Analog temperature measurement
Post by: tpone on March 04, 2008, 16:29:56 PM
I think i found the best solution! I will use a magical IC that measures both temperature and humidity and also is much more precise. I do not need 600 degrees! I hope my pc will never get that hot. If it does i will sure won't look the temperature  :)
Title: Re: Analog temperature measurement
Post by: Andre on March 04, 2008, 19:24:57 PM
Of course is the best solution as long as it covers your needs. Check the Humidity and Temperature Sensor - FOST02
Is cheap (less than 10E) end very good. I took 3 for my house!
Title: Re: Analog temperature measurement
Post by: tpone on March 20, 2008, 02:40:15 AM
This is a really eet gadget! I took a couple of them for test and i love it. I hope they are accuarate enough  ;) ;)
Title: Re: Analog temperature measurement
Post by: Erkeli on March 20, 2008, 16:28:46 PM
But their accuracy is standard, very good, and written to it's manual... Check it out.
Title: Re: Analog temperature measurement
Post by: kourt on March 27, 2008, 17:35:23 PM
FOR TEMPERATURES MORE THAN 400 DEGREES ,THE RIGHT SENORS TYPES ARE THE THERMOCOUPLES.THE SIIGNAL THAT YOU HAVE FROM THESE SENSORS IS A FEW mVolts.THERE ARE ABOUT TEN TYPES OF THERMOCOUPLES.FOR EXAMPLE : TYPE K ( NICKEL - CHROMIUM),TYPO T (  COOPER-NICKEL ), TYPE E ,TYPE R ( PLATINUM , TYPE Y , TYPE J etc.  . IF SOMEONE NEEDS I HAVE ALL THE TABLES , FOR ALL TYPES OF THERMOCOUPLES , WHICH YOU CAN SEE THE RELATION BETWEEN TEMPERATURE AND mVolts.
 SO, FIRST OF ALL YOU MUST LEARN WHAT TYPE OF THERMOCOUPLE YOU HAVE AND AFTER YOU CAN USE ONE  TEMPERATURE TRANSMITTER AND YOU WILL HAVE AN ELECTRIC SIGNAL 4-20mA.

FINAL THERE ARE SOME TEMPERATURES CONTROLLERS WHICH THEY TAKE FOR INPUT ALL THE TYPE OF THERMOCOUPLES , AND THESE CONTROLLERS HAVE DISPLAY, ALSO THEY HAVE TWO OUTPUTS RELAYS
IF YOU WANT TO USE THEM.( EXAMPLE TYPES FOR CONTROLLERS : JUMO , YAMATAKE , SELCO
Title: Re: Analog temperature measurement
Post by: tpone on March 27, 2008, 22:16:36 PM
Thanx Kourt for you answer.

I would like to advice you something. Writing in capital letters in forums or chat is... as per savoir vivre, is extremely rude and also very difficult to read.

What you post is very interesting and of course all of us would like to share knowledge, that's why forum exists after all. So if you have any tables or data, send them either to the forum by post or contact administrator (his id is kam) and send him by emal so he can make a new page with your supply data.

Actually, we all try to make this site better. That is the idea.

The solution i gave is by using the Maxim DS1621 that can measure digitally from -15 to +105 degrees C with great accuracy (0.5 degrees step) and error less than 0.2 degrees.
Title: Re: Analog temperature measurement
Post by: spic0m on March 28, 2008, 00:34:10 AM
WHY DO YOU SHOUT? In foroum writting, capitals mean that you are screaming to us, please don't do that.
Title: Re: Analog temperature measurement
Post by: kam on March 28, 2008, 00:46:53 AM
lol ok. i think he got the point.
Title: Re: Analog temperature measurement
Post by: spic0m on March 28, 2008, 09:57:47 AM
Anyway, welcome to the foroum kourt and indeed, upload any datasheet or diaggram you have, i 'll tell a secret the admin is hidding. :) :).
In a few days the server will be upgraded and triple its storage capacity, so we all have more space to upload!  ;D  ;D  ;D  ;D  ;D
Title: Re: Analog temperature measurement
Post by: kourt on April 04, 2008, 22:05:04 PM
I found the way to post  a table with  the relation beetwin temperature and μVolts for type K thermocouple.
Title: Re: Analog temperature measurement
Post by: manley_V on April 04, 2008, 22:24:10 PM
Great Kourt!
Title: Re: Analog temperature measurement
Post by: kam on April 04, 2008, 22:44:00 PM
Keep up the good work man.

And make a new PLC project

I know you can!
Title: Re: Analog temperature measurement
Post by: kourt on April 04, 2008, 23:01:09 PM
The most classic temperature sensors are PT-100.
It means that for 0 deg. you have 100 Ohms.
look the table.......
Title: Re: Analog temperature measurement
Post by: kourt on April 04, 2008, 23:55:27 PM
Special  ;D
Title: Re: Analog temperature measurement
Post by: kam on April 05, 2008, 00:16:52 AM
Send some more and i will make a nice theory page for these