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### Topic: Constant current hot wire anemometer (Read 4256 times)previous topic - next topic

#### Hasan021

##### Jan 28, 2017, 04:44 pm
Hi

I want to construct a constant current hot wire anemometer. After designing the circuit, i started to build it. As i am studying in mechanical engineering, i have a little knowledge in arduino. The theory of the project told me that when the air flows over the hot wire,it's temperature changes. this change can be expressed by wire resistance. But i am in deep trouble how i get the air velocity from wire resistance by arduino. If anyone would come forward to help me,it will be great help to me. Is there any sample arduino code which i can use for my project? Here is my circuit diagram:

#### jremington

#1
##### Jan 28, 2017, 04:51 pm
You will need to calibrate the thermometer in a wind tunnel under temperature controlled conditions.

#### AWOL

#2
##### Jan 28, 2017, 05:09 pm
You will also need to STOP CROSS-POSTING

Duplicate deleted.

#### arduinoaleman

#3
##### Jan 28, 2017, 05:29 pm
A hot wire will cool off much less at 104 gedrees (40 Celsius) than at 32 degrees (0 Celsius).

So using the cooling effect for detecting wind speed is just an idea. Not even a good one.

Sorry , but you would have so many many mathematical calculations to conuntereffect the temperature changes, that it is NOT worth the project.

However, this is why PROJECT GUIDANCE on this forum exists.

There are proven methods of measuring wind speeds.

If your questions are not precise, nobody can help you.

#### AWOL

#4
##### Jan 28, 2017, 05:43 pm
Quote
So using the cooling effect for detecting wind speed is just an idea. Not even a good one.
It's such a bad idea that NASA have been using it for planetary landers for decades.

#### arduinoaleman

#5
##### Jan 28, 2017, 05:57 pmLast Edit: Jan 28, 2017, 06:09 pm by arduinoaleman
Aneometer = wind speed meter

Landing on the Moon or on Mars an aneometer will not help.

NO ATMOSPHERE = NO WIND.

The basic question was about measuring wind speed.

Of course you can use any device that is capable of feeling temperature diffenences to detect external temperatures.

When coming closer to the moon any temperaure sensor will tell you it is getting warmer.

Like the earth the moon can store warmth.

Lets get back to the start:

The whole thing was about measuring wind speed, indirectly with temperature changes.

So NASA was not wrong, you were not wrong, and my ideas are not really strange.

If your questions are not precise, nobody can help you.

#### AWOL

#6
##### Jan 28, 2017, 06:20 pmLast Edit: Jan 28, 2017, 09:34 pm by AWOL
Aneometer = wind speed meter

Landing on the Moon or on Mars an aneometer will not help.

NO ATMOSPHERE = NO WIND.
Mars has an atmosphere, dumbass.(sp."anemometer")

Quote
When coming closer to the moon any temperaure sensor will tell you it is getting warmer.

Like the earth the moon can store warmth.
Can you spell "non sequitur"?

Please stop changing the topic title when you reply

#### jremington

#7
##### Jan 28, 2017, 06:41 pmLast Edit: Jan 28, 2017, 06:42 pm by jremington
Quote
When coming closer to the moon any temperaure sensor will tell you it is getting warmer.
I checked one of my temperature sensors, and that is not the case.

#### allanhurst

#8
##### Jan 28, 2017, 07:07 pmLast Edit: Jan 28, 2017, 10:30 pm by allanhurst
[jremington : handy to have a moon temperature thermometer - how did you do it?]

Most modern cars have a mass air flow sensor using exactly this principle.. ..so it's possible

They use two identical wires in the airflow  : one heated, one not ( to compensate for ambient temperature) .

The current through the heated wire is controlled so as to hold it at a fixed temperature above the unheated reference, and the current required depends on the velocity of the airflow.

Buy one from the major car makers.

Or make your own using two light bulb filaments. (glass enclosure removed!)
Look up the resistivity variation  with temperature of various metals. I think tungsten is about 6ppm/C

Or use 2 small ntc thermistors - their variation is much bigger  - about -4% /C

Calibration would be required, of course.

Allan

#### arduinoaleman

#9
##### Jan 28, 2017, 10:45 pm
Yes, Mars has some sort af atmosphere. My fault. Let it be as it is.

When you are in between Earth and Moon you will have to go another 200,000 kms.

In between Earth and moon it is very very cold.

Coming closer to the moon it will get warmer for a sensor directed at the moon (temperatures on the moon: up to more than 100 degrees on the side we can see - and up to minus 145 degrees on the shady side).

Even Pluto is warmer than its environment (still pretty cold). A temperatute sensor that works at low temperatures should be able to detect this.

Please do not tell me that the avarage temperature on the Moon is 0 degrees Kelvin (minus 273 Celsius).

By the way: NON SEQUITUR ....

I like this, I had to learn Latin for years. I hated it, but it helped me a lot to understand some Italian and learn Spanish.

If your questions are not precise, nobody can help you.

#### AWOL

#10
##### Jan 28, 2017, 10:47 pmLast Edit: Jan 28, 2017, 10:55 pm by AWOL
OK. I don't like repeating myself, or being ignored, and I've already asked youtwice to not to change the topic title in your replies, so please accept the forum timeout.

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