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saeed_pk
Joined: 20 May 2006
Posts: 198
Helped: 5
Location: Islamabad, Pakistan
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 06 May 2009 10:30 400 centigrade |
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Hi all,
I am want to know any sensor which can easily be interfaced with PIC MCU
and can read upto 300- 400° C of Temperate Lower limit not necessary it may be room temp or zero degree Celsius
Please advice a temperature sensor and also tell any equation which may convert R/I/V into temperature.
Some one told me about using thermocouple i don't know how to use it
please advice.
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AMK1971
Joined: 13 Nov 2007
Posts: 35
Helped: 2
Location: 33.688°N73.035°E
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08 May 2009 8:46 centigrade temperature sensor |
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you can use a high gain instrument amplifier to amplify the voltage, usually thermocouple voltages are in range of mili Volts.
Themocouple do not produce linear values and that can be done in software.
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saeed_pk
Joined: 20 May 2006
Posts: 198
Helped: 5
Location: Islamabad, Pakistan
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08 May 2009 11:51 temerature sensor 300-400 degree celsius |
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I have checked that K-type thermocouple increases 40uV on every °C increase in temperature.
Will you please tell me the correct op-amp circuit which scale it up to the voltage that can be easily read by my MCU
What is the minimum limitation b/w VREF+ anf VREF- voltages and what minimum volatge and PIC ADC can read.
Please Help me in this regard.
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hakeen
Joined: 16 Jun 2005
Posts: 152
Helped: 16
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08 May 2009 14:41 thermocouple temperature sensor pic |
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Hi
I guess this document might help, especially for signal conditioning after thermocouple.
http://techtrain.microchip.com/webseminars/documents/SensorSig_040808.pdf
Regards
Hakeen
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FvM
Joined: 22 Jan 2008
Posts: 5044
Helped: 752
Location: Bochum, Germany
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08 May 2009 21:59 400 centigrades sensor |
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400° are also pretty in the usable range of Pt100 or Pt1000 sensors, they need less gain and particularly no cold junction compensation. With higher resolution ADC (16 or 24-Bit), they are often interfaced directly in a simple ratiometric circuit.
I hear from your post, that you are intending to use the internal (10-Bit) ADC for temperature measurement. Unfortunately, the limited accuracy of the internal ADC requires to use the full available voltage span (or at least most of it) for the reference. Thus an amplifier is needed to adapt the ADC span to the utilized voltage range of the sensor circuit. But a single rail-to-rail OP can do in case of a Pt100/Pt1000 sensor. The said ratiometric operation can be achieved however, the measurement then only depends on resistor ratios, not on a reference voltage.
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Nemesis77
Joined: 20 Feb 2009
Posts: 3
Location: South Africa
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11 May 2009 11:01 temperature sensor 300 celcius |
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Check out the AD595 from analog devices. It converts the µV signal from a K-type probe to mV. It outputs 10mV/°C. So at 400°C the output would be 4V. Only drawback is the price of the IC but it is woth it.
You can also check out the AD623. It is an instrumentation amp with adjustable gain. The coefficient is approx 25. i.e. determine the voltage in µV and multiply by 25 to get the Temp in °C.
Also check the attached file.
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DraganM
Joined: 24 Dec 2006
Posts: 32
Helped: 1
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19 Jun 2009 11:48 400 centigrades |
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| Pt100 with IC signal conditioner will give you chip and excellent linearity and 4-20mA output.
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ankit.ec05
Joined: 20 Aug 2008
Posts: 3
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19 Jun 2009 12:57 pt100 |
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| you can use this link "http://www.national.com/appinfo/tempsensors/files/temphb.pdf " for Temperature sensor .
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jit_singh_tara
Joined: 22 Dec 2006
Posts: 110
Helped: 6
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24 Jun 2009 9:07 south africa location degrees centigrade |
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| pt 100 with signal conditionaing circuit......
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ilker_32
Joined: 22 Jun 2009
Posts: 39
Location: Turkey
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25 Jun 2009 11:15 400°c temperature sensor |
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i can't understand. But, examine that.
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kender
Joined: 19 Jun 2005
Posts: 1219
Helped: 86
Location: Stanford, SF Bay Peninsula, California, Earth, Solar System, Milky Way
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Google
AdSense
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25 Jun 2009 16:10 Ads |
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scmael
Joined: 10 May 2008
Posts: 10
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19 Jul 2009 3:19 thermocouple k +centigrade |
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I do not know if aid
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smd_lover
Joined: 19 Jul 2009
Posts: 28
Location: Netherlands
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19 Jul 2009 8:44 islamabad temperature celsius |
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Another possibility is the KTY84 sensor.
It is cheap, but only goes up to 300 degrees Celsius.
It also needs a linearisation circuit.
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