anemometer

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Find the "Heating air in a wind tunnel" thread on this newsgroup and
read it.

I'm going to build simply hot-wire anemometer. It have to work width

3,3V supply. Precision: 1 meter per second. Full scale: 0m/s to 30m/s. Have you any idea?

Run a search through Electronic Design or EDN for design ideas by Woodward- he has several good anemometer designs published. The 3.3V limitation will have to be handled by boost power supplies on board.

He wants a digital circuit anyway.

This might be more in line with what you're looking for:

There was one he published just after that expanding upon the technique and improving the accuracy. Note that his circuits consume *lots* of current too.

Works with thermistors as well. I did such in my Bachelor's thesis on blood flow measurement with catheter-mounted thermistors (MIT/Harvard Med School/Peter Bent Brigham Hospital, 1962).

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

I think it's good idea. This seems to be fine also.

So this method will be more precision?

Hmm. What do You think about idea with Wheatston bridge and broken bulb. Voltage from bridge will be passed on ADC converter.

At least, make it differential,one wire shielded from the moving air, the other not,that gives you temperature compensation,and less dependancy on the type of wire.Feed both wires with a current source, and measure the voltage difference between them.

Burry.

I've got a schematic, but it's Germanium transistors ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

Have You any example schematic or some materials?

Nichrome wire is not costly and is easily obtained. It is durable even when red hot, as in electric heaters.

The disadvantage of Nichrome is that its resistance varies very much less with temperature than that of platinum. But you may get enough variation for your purpose.

--
Regards, John Woodgate, OOO - Own Opinions Only.
If everything has been designed, a god designed evolution by natural selection.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

The best results I should achieve when I'll use a platinum wire, but I have a problem to get this wire.

We have two real ones up on eBay.

-- Many thanks,

Don Lancaster voice phone: (928)428-4073 Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552 rss:

email: snipped-for-privacy@tinaja.com

Please visit my GURU's LAIR web site at

IOW, if you could afford platinum wire, you could afford to hire somebody to tell you how windy it is? ;-D

Cheers! Rich

I couldn't find them.

--
 Thanks,
    - Win

There was the dual metal ball one that was in the Nov 95 issue of "Scientific American" A number of folk got good results from these, and claimed accuracy of a few % and resolution of better than 0.1m/s. However it operates off 9 volts. DC-DC switcher?