Hi. Total noob here. I have a thermistor but I am not sure if I need to wire it ground to analog in or +5. I have it wired to ground and analog pin2 now and am not reading anything. Just worried about breaking things if I wire it to +5. I checked it with a multimeter and it read just fine
You need to wire one end of the thermistor to +5vdc and wire the other end of the thermistor to a new resistor and the other end of the new resistor goes to ground. Then wire the junction of the resistor and thermistor to the analog input pin. The value of the new resistor has to be sized such that the min and max resistance change of the thermistor keeps the desired resulting voltage range for the temperature range you wish to cover.
Would need more info on the thermistor to help figure out the value of the resistor.
Here is an application guide to help explain better then I can.
Lefty
Its an EGT sensor. I used my multi meter and a lighter and measured from near 0 to 20 something ohms. So I would need a 40hm or so resistor. Thanks for the information, this makes perfect sense when compared to a potentiometer (using the sample). Haven't done small electronics since the hobby kit as a boy. I can, however, write code for just about anything.
Does EGT stand for Exhaust Gas Temperature? If so, are you sure it's a thermistor and not a thermocouple? The reading of 20 Ohms sounds way too low to be correct -- should it be 20k Ohms? Or is it really 20 Ohms and you have a thermocouple?
If you do have a thermocouple, adding a 40 Ohms resistor in series will not work. You will need a thermocouple amplifier, such as the chip made by (I think) Analog Devices.
I don't really know either way. Yes, exhaust gas temp. I first checked it for mv (thermocouple right) nothing happened and then resistance with multimeter set to 200. Resistance when from near 0 to 20 under a lighter flame. I assume this means it is behaving as a thermistor? Again, Sorry I haven't dealt with this level of stuff since I was a teenager.
What temperature range does the EGT respond to? Is a lighter flame a reasonable temperature for it? If it's an automotive part, than it may be that they've made a very low resistance thermistor for some reason. Can you find a data sheet for the sensor?
I'm just wondering about self-heating with as low a resistor as 40 Ohms. But then, if it's meant to be in a gas flow of some sort, maybe that's insignificant?
EGT Pyrometer should be up to 2000F or so. A lighter flame is what say 700? No data sheet I pulled this off of ebay but I can only imagine its "standard".
Perhaps it is a K type thermo couple? I found this article : http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1212666601
Sounds like this is what I have to work with. Is there any reason I can't do it measuring resistance?