What is this temperature sensor

[seyyah]

It's used in an environment that goes not above 100 degree celcius. And i believe it's a cheap one.

 

[NIKHILRAJ]

is it a RTD? it seems so .

Resistance Temperature Detectors (RTDs) are
temperature sensors that contain a resistor that
changes resistance value as its temperature changes.

 

[seyyah]

But it has 3 wires . 2 of the wires shows about 42kohms at room temperature and the others show in the megaohm range or open circuit. As i heat it, the resistance drops e.g. it dropped to 34kohms at my experiment.

 

[wp100]

Hi,

Sounds like a NTC Thermistor on the two wires plus a cable shield on the third.

They are rated at 25 deg C so you could have a sensor around one of these typical values 33k, 47k or 50K.

 

[seyyah]

Hi,

Sounds like a NTC Thermistor on the two wires plus a cable shield on the third.

They are rated at 25 deg C so you could have a sensor around one of these typical values 33k, 47k or 50K.

But the controller which it's connected to, applies 5V to the sensor and take measurement from one of the terminals as i inspect the card.

 

[wp100]

Hi,

A basic ntc circuit would be as below - only 2 connections to the ntc.

You say you are measuring voltages on the circuit board connector to the sensor but you do not relate them to the ohms test details you originaly posted .

 

[FvM]

But the controller which it's connected to, applies 5V to the sensor and take measurement from one of the terminals as i inspect the card.

Good, that you finally mentioned this. Seriously, you can't know about the sensor type without watching it in operation. Beside RTD and NTC or silicon PTC sensors, there are also IC sensors with different kind of output signals, e.g. analog voltage, frequency, digital data. Tracing the said output terminal can give a first hint about the sensor type.

 

[Neha007]

I have seen such sensors where a LM35 will be immersed in heatsink compound packed inside similar copper or brass tubes for better heat transfer and these will have 3 wires out. But i am not sure about your sensor as you'll have to carefully open it can confirm if possible.

 

[pranam77]

Yes..i too have seen such setup where a LM35 is covered with the heatsink paste and ecapsulated inside a metal casing.
Cheers

 

[seyyah]

I have seen such sensors where a LM35 will be immersed in heatsink compound packed inside similar copper or brass tubes for better heat transfer and these will have 3 wires out. But i am not sure about your sensor as you'll have to carefully open it can confirm if possible.

Yes you were right, i cracked the housing and there was a LM35 buried in it. Thanks to all.