Digital Gaussmeter

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I made a digital gaussmeter. It's pretty simple and was fun to build.

http://www.avrfreaks.net/index.php?module=Freaks%20Academy&func=viewItem&item_id=1249&item_type=project

It measures between +- 1000 gauss and will hold the highest measured value. It also uses a piezo buzzer to give it some added gizmo novelty.

Attachment(s): 

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it is very clever but do not understand at it is work with 1K serie with Vcc and not cap ????
Thierry

Thierry Pottier

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The resistor doesn't need to be there I guess. At one time I was worried about pumping too much current through the micro controller.

Do I need a capacitor somewhere?

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I ttried your links in the project, but they do not seem to work. Can you U/L a zip file of the material to Freaks?

What sensor did you use? I am interested in making my own gauss sensor. I want to make an electronic regulator for an automotive generator (not alternator!). These devices usually monitor voltage and current, and then raise/lower current in the field wires to increase/decrease the output.

I was thinking about increasing magnetic flux by using a toroidal ring with a slot cut in it and then sliping the sensor in the slot.

-Tony

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Hey sorry about that. I switched my domain name which screwed up the links. They work now.

You have an interesting idea. The hall effect sensor I used was from Allegro Microsystems (http://www.allegromicro.com/en/). I requested a free sample of their A1301.

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Thanks for that info. I had been thinking of using the same devices. THe toroidal ring would be useful for current through a wire, but not helpful(?) for measuring a plain old magnetic field.

I presume that it measures the field lines perpendicular to the flat face of the sensor. If you turn the face perpendicular to the magnet, does the reading drop?

Re: capacitor. You should have one on the power input to the CPU. You should have some sort of low pass filter on AVCC too.

-Tony

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Yes, the sensor measures the magnetic field in relation to its perpendicular faces. The reading with no magnetic field is about 2.5V. Depending on the magnet polarity and which side of the hall effect sensor is used, the output voltage will either rise or fall when it is rotated.

Couldn't you use a circular coil with N turns? The strongest magnetic field would be right in the center perpendicular to the coil.

As for the LP filter, we just covered the topic in my electronics class. It's funny because I reread my post before you brought it up and I was thinking to myself, "He probably meant a lowpass filter."

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Yes, A simple coil (solenoid) would work, but the toroid helps to contain the flux lines and will give a higher reading on the sensor. Also if there are other EM sensitive devices, it is a good idea to contain the magnetic flux.

Extra turns of the wire around the toroid will proportionally increase the flux, just like a regular solenoid.

-Tony

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why i cant open your project..URL...i really need to see it

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... maybe because he left 3 years ago and is gainfully employed elsewhere?

Ross McKenzie ValuSoft Melbourne Australia