Originally Posted by cjhaw

Hi, I am new in using the LM35DZ. I had encountered when measuring a temperature of boiled water by using the connection of basic centrigrade temperature sensor (Fig 1) from LM35 data sheet. Supposed the temperature measured by thermometer is more than 90 'C. But the measured temperature from LM35 is 55 'C which is shown in multimeter 550 mV.

Is there any solution to improve the result? I hope that I can get help from you all.

Thank you.

hi,
I assume you powered the LM35 from 5V thru 9v.??

How did you bring the LM35 body into contact with the boiling water.?

Usually they are accurate to +/-0.5C,

You did the test at sea level or up there somewhere in the mountains?

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Originally Posted by Angry Badger

Hi,

Are you applying sufficient supply voltage?

That's what I was wondering too

Originally Posted by Angry Badger

Hi,

Are you applying sufficient supply voltage?

Hai, thank you for the post. The figure in attachment is the 2 ways I used to connect the LM35 to power supply. The left one show the direct connect of LM35 legs to the power supply. The second one I just connect the two V+ and V- to power supply then from the power supply, the V- connect to GND.

I actually try to follow the value in data sheet. But with the connection, when I tuned my voltage input to 4V, I need higher current (could be up to 0.3 A) and the LM35 itself is getting very hot and give high voltage output than expected. Is there anything wrong with my connection? Thanks.

[QUOTE]

Originally Posted by cjhaw

Hai, thank you for the post. The figure below is the 2 ways I used to connect the LM35 to power supply. I actually try to follow the value in data sheet. But with the connection, when I tuned my voltage input to 4V, I need higher current (could be up to 0.3 A) and the LM35 itself is getting very hot and give high voltage output than expected. Is there anything wrong with my connection?

The LM35 if connected correctly only draws microamps and shouldnt even get warm at 5V.

Check that you have read the LM35 correctly from the datasheet.

We cannot access an image on your PC, scroll down on the Reply window and use the ' manage attachments ' button

I use the LM34, TO-92 package (same device except it reads in F instead of C) right out of the box with regulated 5 volts. Temp readout on DMM will constantly track within .5 degrees my $500 indoor and outdoor thermometers.

Generally, if a part is behaving irradically, it isn't the part.

Originally Posted by cjhaw

I posted my connection of LM35 as well.

Where did you get those connections? Attached is the proper connection from the LM35 data sheet. Very simple. Plus and ground from your power supply, DMM red probe to out and black probe to ground. No problem.