LM35 detection range

Other Hardware Sensors
1

Guys can I ask a question about LM35.
I bought LM35 here in the Philippines for my thesis defense.
I already finished y defense but the problem is the paper revision.
My panels ask me to put the range of this sensor.
Example 1meter from the sensor. After 1 meter the sensor cannot detect the temperature there..

Do you guys have any idea. And I said that LM35 is an ambient temperature sensor. Which means it can detect the temp of the room. But They did not accept that. They said that temp in server room(Where i will apply my sensor) is different in each part

2

It senses the temperature of its immediate surroundings. It does not have a 'range'. If you measure the air in one part of the server room you are making a simplifying assumption. Certainly the air will be hotter at the heat sources and cooler at the air-conditioner outlet.

3

the output of the LM35 is influenced by various effects:

  1. inaccuracy of the internal parts
  2. other non-ideal properties of the internal circuit of the LM35
  3. incoming heat radiation
  4. outgoing heat radiation
  5. heat convection
  6. heat conduction
  7. self heating
  8. maybe others that i forgot or dont know... :slight_smile:

if u have a strong heat source (like an open fire), the range of the LM35 might b some meters...
But normally influences #5 and #6 should b the most important... and that range is just the surface... zero meters i would say...
maybe influence #5 can have some range, if the air stream comes from some distance... :slight_smile:

4

Perhaps the safest route is to say "it measures whatever it is directly touching". If you're measuring air temp, make it touch the air, if you're measuring a server rack, stick that baby on the heat sink!

5

hye, i have a problem with LM35.. my sensor just detect only a value which is 31*C no matter how hot a day is and how cold a day is..

here i include my coding

float tempC;
int tempPin = 1;
int val;
float time;

//write setup fn

void setup()
{
Serial.begin (9600);
}

//loop

void loop()
{
val = analogRead(tempPin);
float tempC = val*0.0303030303;
if (tempC>30)
{
Serial.print("Time: ");
time = millis();
Serial.println(time);

Serial.print("TEMPERATURE= ");
Serial.print(tempC);
Serial.print("*C");
Serial.println();
delay(3000);
}
}

6

Why are you hijacking a five year old thread?

Always use code tags to post code.