Tesmistor: chilichonse chomwe muyenera kudziwa kuti muyeze kutentha mumapulojekiti anu

otentha

Ma sensa osiyanasiyana otentha afufuzidwa munkhani zina. Chimodzi mwazinthu kapena zida zomwe mungagwiritse ntchito kuyeza kutentha kumeneku ndizomwe zili otentha, mu Chingerezi thermistor (thermally sensitive resistor kapena kutentha thunzi kukana). Monga momwe dzinalo likusonyezera, zimachokera pazinthu zomwe zimasintha mphamvu zamagetsi kutengera kutentha komwe kumayikidwa.

Mwanjira iyi, pogwiritsa ntchito njira yosavuta, podziwa mphamvu ndi mphamvu yomwe imayikidwa, kukana kumatha kusanthula kudziwa kutentha molingana ndi msinkhu wake. Koma sikuti imagwiritsidwa ntchito ngati sensa yotenthetsera, itha kugwiritsidwanso ntchito kusintha mawonekedwe azizungulira kutengera kutentha kwake, ngati chinthu choteteza kuzowonjezera zaposachedwa, ndi zina zambiri.

La kusankha mtundu wa sensa Zomwe mugwiritse ntchito pulojekiti yanu zimatengera zosowa zomwe muli nazo. Zolemba zina zomwe zingakusangalatseni za masensa otentha:

  • LM35: Kutentha ndi chinyezi sensa.
  • Zogwirizana: kachipangizo kutentha kwa zakumwa.
  • Zamgululi: kutentha kwachangu komanso chinyezi.
  • Zamgululi: kutentha kotchipa komanso chinyezi.

Mau oyamba a thermistor

chizindikiro cha thermistor

Mumsika mungapeze zambiri otentha ndizolemba zosiyanasiyana komanso zamitundu yosiyanasiyana. Zonsezi zimakhazikika pamfundo yomweyo, zida zawo za semiconductor (nickel oxide, cobalt oxide, ferric oxide, ...) zidzasinthidwa kutentha kukasiyanasiyana, ndikusintha kukana kwake kwamkati.

Mitundu

Pakati pa mitundu ya thermistor titha kuwunikira magulu awiri:

  • NTC (Wachisoni Kutentha koyefishienti) Thermistor: otenthawa oterewa amakhala ndi cholumikizira cholakwika, kutentha kumawonjezeka, kuchuluka kwa omwe amanyamula nawonso kumawonjezeka, chifukwa chake, kukana kwawo kumachepa. Izi zimawapangitsa kukhala othandiza kuti azitha kugwiritsidwa ntchito ngati:
    • Masensa otentha omwe amapezeka pafupipafupi m'ma circuits ambiri monga otsika otentha otsekemera, m'galimoto zamagetsi pazoyesa zamainjini, muma thermostats a digito, ndi zina zambiri.
    • Kuyambira malire omwe alipo, mukamagwiritsa ntchito zinthu zomwe simufuna. Pakadali pano pakadutsa pomwe gawo limayatsidwa, chipangizochi chimayaka chifukwa cha kukana komwe kumabweretsa ndipo kutentha kumawonjezeka, kukana kumachepa pang'onopang'ono. Izi zimalepheretsa kupitiliza kwa dera kukhala lokwera kwambiri koyambirira.
  • PTC (Makhalidwe Abwino Otentha) Thermistors: Ndi ma thermistor ena omwe amakhala ndi kutentha koyefukira koyenera, okhala ndi ma dopant okhala kwambiri omwe amawapatsa mphamvu zotsutsana ndi ma NTC. Ndiye kuti, m'malo mochepetsa kukana ndikuwonjezereka kwa kutentha, zotsutsana zimachitika mwa iwo. Pazifukwa izi, atha kugwiritsidwa ntchito ngati mafyuzi oteteza ma circuits opitilira muyeso, ngati timer yothetsera ma CRT kapena ma cathode ray chubu, kuwongolera ma motors, ndi zina zambiri.
Chithunzi cha NTC thermistor

Zithunzi za curve yotsutsana ndi kutentha kwa NTC

Osasokoneza thermistor ndi RTD (Kutsutsa Kutentha chowunikira)Popeza, mosiyana ndi iwo, ma thermistors SASINTHA kukaniza pafupifupi mzere. RTD ndi mtundu wa thermometer yolimbana kuti izindikire kutentha kutengera kusintha kwa kondakitala. Chitsulo cha izi (mkuwa, faifi tambala, platinamu, ...), chikatenthedwa, chimakhala ndi kutentha kwakukulu komwe kumamwaza ma electron ndikuchepetsa kuthamanga kwawo (kumawonjezera kukana). Chifukwa chake, kutentha kumakhala kwakukulu, kukana kumakulirakulira, monga NTC.

Ma RTD onse, ma NTC, ndi ma PTC ndiofala, makamaka ma NTC. Cholinga chake ndikuti amatha kugwira ntchito yawo ndi kakang'ono kwambiri ndi mtengo wotsika mtengo kwambiri. Mungathe tengani ma thermistors a NTC monga MF52 yotchuka pamtengo wotsika m'masitolo ngati Amazon, monga Kufufuza kwa RTD, komanso m'misika ina yapadera yamagetsi.

Kwenikweni pepala, ili ndi zikhomo ziwiri zokha, monga zotsutsana wamba. Njira yake yolumikizira ndi yofanana ndi ya wotsutsa aliyense, phindu lokhalo silikhala lokhazikika, monga muyenera kudziwa kale. Kuti mumve zambiri zamitundu yolandirira kutentha, ma voliyumu othandizira kwambiri, ndi zina zambiri, mutha kuwona zaaliraza gawo lomwe mwagula.

Kuphatikiza ndi Arduino

Arduino mwatsatanetsatane ndi thermistor

Para phatikizani thermistor ndi bolodi lanu la Arduino, kulumikizana sikungakhale kosavuta. Ndikofunikira kokha kusintha malingaliro ndi kuwerengera kwa nambala yomwe muyenera kupanga mu Arduino IDE yanu. Kwa ife, ndakhala ndikuganiza kuti ndigwiritsa ntchito kachipangizo ka NTC, makamaka mtundu wa MF52. Mukamagwiritsa ntchito mtundu wina wama thermistor, muyenera kusintha malingaliro A, B ndi C kuti musinthe malinga ndi kufanana kwa Steinhart-Hart:

Chithunzi cha Steinhart-Hart

Kukhala T kutentha komwe kumayesedwa, T0 ndiye kutentha kwachilengedwe (mutha kuwerengera momwe mungafunire, monga 25ºC), R0 ndiye mtengo wotsutsana ndi NTC thermistor (kwa ife yomwe idaperekedwa ndi MF52 datasheet, ndipo simuyenera kusokoneza ndi kukana komwe ndawonjezera kudera), ndipo coefficient B kapena Beta imapezeka papepala lazopanga.

El code zingakhale choncho:

#include <math.h>
 
const int Rc = 10000; //Valor de la resistencia del termistor MF52
const int Vcc = 5;
const int SensorPIN = A0;

//Valores calculados para este modelo con Steinhart-Hart
float A = 1.11492089e-3;
float B = 2.372075385e-4;
float C = 6.954079529e-8;
 
float K = 2.5; //Factor de disipacion en mW/C
 
void setup()
{
  Serial.begin(9600);
}
 
void loop() 
{
  float raw = analogRead(SensorPIN);
  float V =  raw / 1024 * Vcc;
 
  float R = (Rc * V ) / (Vcc - V);
  
 
  float logR  = log(R);
  float R_th = 1.0 / (A + B * logR + C * logR * logR * logR );
 
  float kelvin = R_th - V*V/(K * R)*1000;
  float celsius = kelvin - 273.15;
 
  Serial.print("Temperatura = ");
  Serial.print(celsius);
  Serial.print("ºC\n");
  delay(3000);
}

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