unknown temeperature sensor (RT103)

[Richman87]

Hi

I have a PCB of commercial digital clock, it contains a " temperature sensor with two wires" labeled on board as "RT103".

I want to use this sensor in another DIY project but I couldn't find its datasheet.

Do you have Any info. about this sensor?

 

[paulfjujo]

hello,

maybe a Pt1000? 103 for 10^3
can you measure this device with an ohmmeter?

 

[wp100]

Hi,

Could be a pt1000 as Paulfjujo suggest, though think if you measure its resistance is more likely to be a 10kohms and a NTC.

Would not have thought a digital clock would be likely to use an expensive RTD sensor.

 

[Richman87]

I've measured its resistance in a cool room, it's about 11 kilo Ohms.
here is the sub-circuit:


Can you figure out how the MCU read the temperature?

 

[wp100]

Hi,

Its almost certainly a 10K NTC, it should measure 10K in a room Temperature Ta of 25deg C.

If you increase the temp then the resistance should fall, if it increases then its a PTC.

Plenty of datasheets around for 10K NTC, though the problem is they do not have a perfectly linear slope of resistance v temp.

You use the ADC input of a mcu to read the voltage, but need a good bit of code to convert the adc reading to a temp on a display.

Something like a linear LM35 is a much easier sensor to use or a DHT11 which does temp and humidity, both having projects well documented in this forum.