Jim Koehler's magnetometer plans

[Kitsune]

Jim Koehler's magnetometer plans were also published in honest to god dead tree magazine Circuit Cellar, this years May issue (5$ in USA)

[jocaps]

Proton Magnetometer

Please send me to the complete plans of proton magnetometer this is my email Add: [email protected]

[golddigger]

Koehler's mag

Jim Koehler's magnetometer plans were also published in honest to god dead tree magazine Circuit Cellar, this years May issue (5$ in USA)

The plans that are in Cicuit Cellar are for a new version that uses phase shift rather than counting of the precession frequency. The new version leaves the sine wave as is while the old version converts it to a square wave and then counts to a set amount. After reaching that it stops the 10mhz clock. This is then converted to a reading.

I have Jim's original schematics and he was also kind enough to provide me with his source code. The source code was incomplete as had lost the final versions and I had to modify it to make it useable. I never did master the UART that Jim uses to communicate between the slaves and the master however I did rewrite the code to make a simple magnetometer.

I don't see the schematics in the writeup that is posted on this site. This is my first visit to the forums here and it is possible someone has already provided all the info on Jim's gradiometer.

[Unregistered]

JimKohlersMagCopy

This is NOT the site describing the Jim Koehler's mag but the differential mag of Dan Fountain. However, the one from Jim, currently out of reach, is a much more detailed document supported by a very good principle description. If anyone is interested, I have made a copy of his main documents in PDF. Send me an email and you will get a copy of what I got.

Willy

Dear Willy Bayot,

I am very interested in a copy of Jim Koehler's proton magnetometer. Could you please send me a copy to my e-mail?

Thank you.
mr.BULENT KARAOGLU
[email protected]

[wal59]

Hi Willy,
Im also very interested in a copy of Jim Koehlers PM. Could you pls send me a copy at [email protected].

Thanks
Wal59

[wal59]

Correction [email protected]

[Unregistered]

Jim Koehler's magnetometer

willy,
could you send me a copy of jim's plans?
many thanks,
[email protected]

[Unregistered]

Willy,
Please send me the mag info to:
[email protected]

[Unregistered]

Me as well, and thank you for your time and effort.
[email protected]

[quink]

please post the plan here, thankx

[fisjm]

Jim Koehler's magnetometer

Dear Willy Bayot,

I would like to get a copy of the plans for the magnetometer. My college student is in a club and is interested in building one. If you have any recommendations for other plans that would be most helpful.

thanks,
janet
[email protected]

[fisjm]

Dear Willy Bayot,

I would like to get a copy of the plans for the magnetometer. My college student is in a club and is interested in building one. If you have any recommendations for other plans that would be most helpful.

thanks,
janet
[email protected]

[joco000]

Hi,

Can you please tell me if anyone build this magnetometer

(http://www.jandspromotions.com/phili...ers/AR1746.htm)

There was a lot of requests for schematics, but no feedback if you succesfull build it.

Why no one shows results here ?

I intend to build , and would be nice to know the results from you guys that you alredy build it.

best regards,
Joze

[Seden]

Dr. Koehler's newest Magnetometer Kits

Here is the website for the latest Koehler PPM.

http://users.skynet.be/fa352591/index.htm


Randy

[Owl Face]

Doesn't look like it works

Hi,

Can you please tell me if anyone build this magnetometer

(http://www.jandspromotions.com/phili...ers/AR1746.htm)

There was a lot of requests for schematics, but no feedback if you succesfull build it.

Why no one shows results here ?

I intend to build , and would be nice to know the results from you guys that you alredy build it.

best regards,
Joze

Well, I haven't built the hardware but at this point don't think I am going to. So I saw the Philips contest design you are referring to. I then bought the circuit cellar article with the intent to build Koehler's mag. It is using the phase slip method that he and Willy Bayot use in their magnetometer kit. I bought the Keil MCB2130 development board. I loaded the hex file from the Philips design contest files and downloaded it to the lpc2138 ARM controller. I connected up my laptop running Hyperterm via the serial port on the dev board. It displayed a menu with the functions appearing to work as stated. I connected up a signal generator set to 2128Hz (50,000nT). The readout was 50,082nT approximately. Then I adjusted the signal generator to 2127Hz expecting the resulting nT to be about 23nT less but it also read 50,082Hz. I then went down to 2126Hz and the nT went down as expected. So as I did this I found that the nT displayed did go down as expected except every 4 or 5 Hz and the nT did not decrease. I did try this with higher frequency values as the expected frequency is set to 55,291nT but still got the same strange results.

So as I see it from this test, the base nT calculated is incorrect showing with 2128Hz expecting 50,000nT but getting 50,082Hz. And every 4 or 5 Hz the nT value did not change at all with all readings being high. My signal generator is working fine. I looked at the C code (which I can't compile with the demo version of the Keil compiler supplied with the development board) and it appears to be the exact same with no changes between the Main.C supplied from the Philips contest files and that from the circuit cellar article so no changes were made to correct any errors that I could tell. I also looked through the code (which I don't fully understand admittedly) and found some things I didn't understand like the variable offset which is declared, set to 0.0, and then never used. At this point I wonder if this is the same code Willy and Jim use in the Mark series kits and I don't plan to build this mag any further. Anyone else attempted this? Is it possible I'm missing something? If I could get a corrected copy of the Main.C I'd like to continue building this project if anyone has done this.
Owl Face