What to use thermocouple or thermistor???

[princez]

Hi,
i am doing a project ; whose part is to measure patient's temperature. can any body help me with the sensors???

what to use thermocouple or thermistor??

Please refer some links and circuit designs.

(thx in advance for helping me ).
Regards.

 

[wp100]

Hi,

The thermocouple is becoming obselete and is generally used in wide range or high temp applications.

Of the two devices, the thermistor is probably more suited measuring human temps.
Its simple to use with direct input into a micros adc. It can easily deliver results to 0.1deg C

There are lots of thermistor / NTC circuits in this forum and on the web.

 

[princez]

oki; thx.. i'll search it.
but if u can upload it here it would be quiet helpful.
thx again.

 

[cocoloco]

Ds18s20 One Wire Precision Temperature sensor,Now i use only This in My Project.

you can attach multiple sensor on single wire.

 

[karesz]

Hali,
Or for industrial usages are lot of (a very nice, small-robust) PT-100 or PT1000 to buy. They are even precious and light to handel-> ~as thermistors too...
Good knowed vendors are: jumo/Sensirion & much others...
https://pdf1.alldatasheet.com/datasheet-pdf/view/157816/RHOPOINT/PT100.html
K.

 

[princez]

a big thx for ur kind suggestions.

am going to work on thermistor; if it dosent work then i'll move to DS ic.

 

[karesz]

your welcome!
these is a typical PT1000(only I didnt find it before..)...
Good progress!
K.
I believe; Microchips Tech Note is really valuable to read...

 

[nikhil_damle]

if it is just for demo then use LM35dz simple eazy temperature sensor with direct output without any processing required, if it need precision use lm35 & interface it with a microsontroller for processing

 

[princez]

should i directly connect lm35 with pic?(am using pic16f877a) its got built-in ADC.
does lm35 has that much precision and resolution to detect body temperatures :S
i have previously used lm35; but that was for higher temperature.

 

[karesz]

Hi princez,
I think, the LM35 is not the best body-temp meter, because it has a typical +/- 1Cels. accuracy, but it can be up to +/-2 Celsius :-(...
You can have better thermistors.
Otherwise; of course you can connect it direct to PIC, but it is to realize, that its 10mV/Celsius is not very high voltage, specially for body temp measuring is usual to wish 0.1 degree resolutions tho have, its here 1 mV-relative small for exacter readings_or you have to amplify it.
K.
ps:
I applyd LM35s _for "on PCB temp". to measure, for that they are very good_for body temp more poor...

 

[princez]

yes i too think so that thermistors are more suited; didn't start to work with it right now, cuz busy in other projects, i will soon be pursuing it.

thx everybody!