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Re: Parallax/Hitachi HM55B Compass Example

Started by toahatt March 7, 2007
> It's located 20cm above the 3mm alu plate, on the opposite side of
the motors... and I always have everything turned off while measuring...

The aluminum won't offer much protection. The motors are just too
close, I think you'll find.
Tom
--- In b..., "Tom Becker" wrote:
> > It's located 20cm above the 3mm alu plate, on the opposite side of
> the motors... and I always have everything turned off while
measuring...
>
> The aluminum won't offer much protection. The motors are just too
> close, I think you'll find.
> Tom
>

any tips on what I could use to shield off the fields from the motors?

I just got hold of a basic stamp, so I'm trying the calibration program
there, but some kind of shielding is probably needed anyhow.

Anders
> ... any tips on what I could use to shield off the fields from the motors?

Magnetic "shielding" isn't, really, it is redirection by an intervening
material. You will find it difficult to control the fields from the
motors to create a uniform field around a close-by sensor that
accurately follows Earth.

_Distance_ is your best tool and it is very effective. Again, a
magnetic field decreases quickly as you move away from the source - by
the inverse square, so you'll find a quarter of the magnetic field at
only twice the distance. If you are 20cm from the motors now, you'll
find that 40cm will be four times better, 160cm will be 64 times better,
320cm will be 256 times better than 20cm. Distance is natural,
effective and cheap; look at how magnetometers are mounted to
spacecraft, for example - at the end of a long arm, despite a large
budget. _Distance_ is your tip.

But, if you insist, your path will likely be expensive. Here's one
source of M-metal (US$180 for a sample kit):
http://www.advancemag.com/Credit_Card_Form2.htm

Good luck.
Tom
Hi

Would any of you gentlemen happen to have source code for the
QTl Line Sensor from Parallax.

If you wouldn't mind sharing it that would be appreciated.

Thanks
Ryan
http://www.parallax.com/dl/src/prod/QTISrcCode.zip

On 09 Mar 2007 04:23:42 -0800, Ryan Autet wrote:
>
> Hi
>
> Would any of you gentlemen happen to have source code for the
> QTl Line Sensor from Parallax.
>
> If you wouldn't mind sharing it that would be appreciated.
>
> Thanks
> Ryan
>
>

--
Scott
www.AntiFuel.com

Minds are like parachutes, they only function when they are open.
Here is another:
http://www.parallax.com/dl/src/prod/FasterQtiSubroutineSource.zip

On 09 Mar 2007 04:23:42 -0800, Ryan Autet wrote:
>
> Hi
>
> Would any of you gentlemen happen to have source code for the
> QTl Line Sensor from Parallax.
>
> If you wouldn't mind sharing it that would be appreciated.
>
> Thanks
> Ryan
>
>

--
Scott
www.AntiFuel.com

Minds are like parachutes, they only function when they are open.