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Topic: Is this indeed a 10k thermistor? (Read 1 time) previous topic - next topic

XOIIO

Hey everyone once and a while I have come across one of these tearing down UPS systems and other power supplies.



I was wondering, is this indeed a 10k thermistor? At room temp it measured 80 oms, a bit warmer on my skin and it dropped to 78.9 ohms, I put it in a freezer for a short time and it went up to almost 90 ohms.

It would be fantastic if this was a regular old 10k thermistor because I lost my zip lock baggie of them and will have to wait at least three weeks for some off ebay, but also because the plate with a screw hole which is exactly what I need. I was really hoping someone knows exactly which one this is and link to a datasheet, because I'd love to order some of these too for when I need the temperature of a heatsink or other metal surface, screwing it on would be way better than just pressing the usual style against the heatsink.

jremington

A 10K thermistor has a resistance of about 10,000 ohms at room temperature.

MarkT

A multimeter and warming it with your fingers would be able to show
if it is...
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

mortenx

how to power 10k thermistor for preventing self heating?
if powering thermistor with arduino 5v all day , its geting warm.
is it possible to power thermistor only  at measuring time? digital write?

nightcrawler218

You may use a heat sink tied to the top hole of the thermistor or you can use a resistor "in series" for limiting the current passing through the thermistor. You have to read the datasheet first to know the ratings & specifications of the thermistor.

As you said, the thermistor is self heating.... the probable reason may be that the thermistor is handling more power than it is supposed to handle. Suppose it is a 1/4 watt device but it is forced to handle more than that. in this case the thermistor can overheat or may burnt out as well. it is safe to use another resistor in SERIES to limit the current

In a simple way...
Volt X Current = Power
more volt X more current = more power
more power = more heat generated
so, if you decrease the current or voltage, you can reduce the heat.
I hope it will be helpful to you.
"Imagination is more important than knowledge."<br />-Einstein

mortenx

but what is the simple way to give power to thermistor only that time when measuring ..?

nightcrawler218

I/o pin for 5v----------------- resistor ------ Thermistor-------------GND
                                                                     |
                                                                     |      Acts as a voltage divider
                                                                     |
                                                                     |
i/o pin for ADC reading------------------

You can use any pin for 5V supply but you have to use ANALOG pin for the adc reading. the resistor & thermistor junction will act as voltage divider. connect the ADC pin in that junction now accoording to the change of temperature the resistance of thermistor will change & the o/p of the voltage divider will also change. read the adc value of the divider. If you have the datasheet of the thermistor you can calculate the temperature from the chart.

The whole circuit & reading process will only be in action if the 5V pin ( as mentioned before) is ON. Control that pin according to your need. you can save power & the thermistor will only be activated according to how you program it.
"Imagination is more important than knowledge."<br />-Einstein

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