Rctime and ntc

[aratti]

NTC are negative termoresistor. Which means that while temperature increases resistance of the termistor decrease, so they are inversely proportional.

Al.

[Archangel]

RE: Yes it does but it does not mean they are linear, which is why I do not think simple division will have accuracy.

[larosacristian]

thanks for the answers, I do not need to be precise I just have to control the switching on and off at a given temperature a fan then, that there is an error of a degree I do not care.

[AvionicsMaster1]

Of the one specific thermistor I looked I downloaded the excel file and from 0 degree to 100 degree the curve is indeed exponential. I tried to import the data into excel but I've forgotten how to get it to give you a formula to fit the data entered. I browsed a few others and they all look about the same but you can find the math for a precise formula at http://www.epcos.com/web/generator/W...dardizedRT.pdf. Putting that into PBP will be a challenge to say the least.

This site though has a much easier formula if you know a little of your thermistors' data:http://www.mstarlabs.com/sensors/the...libration.html

Though I thought this site gave you a better idea of how to find the right formula:http://www.cantherm.com/products/the...osing_ntc.html

[larosacristian]

thank you very much I will try to set formulas in pbp and let you know. thank you very much. if someone already has some sample code that can assist me I would be most grateful if you would provide me. greetings