hey guys i am using lm35 temp sensor for my arduino project. the temp it shows after conversion is 35.18 c. however even if i put my fingers on it and press it the temp rises upto a max 36.18 c. in some videos of lm35 i saw the temprature increases at higher rate when pressed so the senstivity must be high but this doesnt seem to be in my case. how to check whether it is working properly or not. i do not have any soldering rod by the way.
Be sure to connect it correct. Use the internal voltage reference to incease sensivity
if i change aref to 1.1v will it affect my other sensor reading connected to different analog pins? isn't there a way to change aref for one pin only?
Sorry. I think this can not be done.
That means U are stuck at 1/2 deg steps.
Of course, U can add a simple amplifier.. at the same cost as a better suited sensor.
Reading the Atmega 328 datasheet it should be perfectly possible to change the voltage reference for different samples but you will need to be careful to follow the Atmel guidelines to get valid results.
...R
Hi, have you read the data sheet and its suggested applications, I suggest you measure the output of the sensor with a DMM until you get acceptable readings.
Also in the top of this page is a "Search the Arduino Forum"
try "LM35" search and see what comes back, you are not the only one using this device.
Tom...... 
Hello I didn't want to start new topic so here it is
I have little different problem, I have singe used lm35 dz which I got with arudino starter kit, for a long time, and I for my next project I needed few more temp sensors, I ordered few of them, but they show wierd analogreading
This is orginal lm35 sensor working like is should
and this is new lm35, I got 5 of them and all 5 "work" the same way
at first I thought maybe its different one, maybe I need different formula or something, but it even doesent sense changing tamperature if I heat it up, analog read and temp stays the same.
post code and connection
add R from Uout to GND. range 33k..100k.
?? are your 'new' sensors LM335 ?
this is formula I use for temp
temp = (5.0 * analogRead(tempPin) * 100.0) / 1024;
and for AnalogRead I just read analog input as it is...
I connected both sensors like on your diagram
Vs --- 5V arduino
Vout --- A0 arduino
GND --- GND arduino
and I messured both of them like you said the old one which work fine had 46k ohms , and "new" one have 37k ohms, but when I connect it the same way like old one, temperature and analong input does not change at all if I am heating or colling sensor.
I dont know if its allowed to show products here... I will remove if its not allowed but I bought this exact product
..your measurements is not relevant..
If theese components are clearly marked "LM35", they should behave like your 'original'.
U say u got 5 - none 'working'.. Contact dealer!
............
The LM35 shall give u a voltage following 'a' in the diagram
Besmrtnik:
and I messured both of them like you said the old one which work fine had 46k ohms , and "new" one have 37k ohms,
You should be measuring voltage - not resistance. Of course the voltage will only be produced of the chip is powered up.
...R
Hi, can you measure the voltage across the sensor resistor at its leads please.
Tom.......
ok on good working lm35 voltage is 0.25V
and on this new ones, its 3.73V
Giving you 3V+ is NOT a working LM35, unless it is placed in an active vulcano.
That chip is defective or it it not a LM35
both of them good and bad one, says LM35 DZ...
it seems that I will have to contact seller...