Hi all, Here is a circuit I did some experimenting with a while back. I just found it looking through some old files. What I remember of it is that it worked...
... Hi John! I've disabled attachments for the group to avoid virus/worm posts. Please either upload the file to the files section of the group or email it...
Hello, This email message is a notification to let you know that a file has been uploaded to the Files area of the magnetometer group. File :...
magnetometer@yahoogro...
Jun 12, 2004 8:09 pm
307
Hi! I´m new to this group so I think I should start by introducing myself. I´m Guillermo Stuarts, from Argentina, and I´m studying Electronics Ingeneering. ...
... Guillermo, Welcome to the group! This is an interesting project and rather than offering thoughts on your choice of magnetometer I have a question about...
Joseph DiVerdi
diverdi@...
Jun 13, 2004 9:56 pm
309
First of all thanks for answering so soon! We do intend to measure the change of the terrestrial magnetic field and we are aware of its changes and the ...
... Guillermo, You're welcome. I, for one, would welcome learning about your actual measurements. If appropriate, feel free to mail me off list otherwise let's...
Joseph DiVerdi
diverdi@...
Jun 14, 2004 3:50 am
311
I finally purchased an FGM3 and associated circuitry for my local data recording station. As of now the device is just sitting on a desk in the office but it...
Not a clue. I can only surmise that the sudden movement causes the FGM3 to give a reading that overloads the digital portion of the converter, causing it to...
... Hello John I have the same issue with the same installation. I move it slowly about 1 degree and it locks up. Richard __________________________________ Do...
I would suggest that if sudden motion is causing lockups in the signal processor, that you have a bad connection somewhere. Easy to find. Take an insulated...
It is clearly the sensor. The circuit board is fastened down on a heavy board with standoffs and screws. The sensor is at the end of a 4 leg cable of ...
... I thought an intermittent connection might be the cause for mine and I touched up all connections. My circuit board setup is the same. The sensor has a...
Sounds like bad connections are not our problem. I wonder what the acutal mechanism of this problem is? jn ... __________________________________ Do you...
John, I believe what's happening here is that as the sensor is moved, the field strength it's 'looking' at is changed by an amount that exceeds the dynamic...
... I have my sensor pointing e/w. I just measured mine and I see 145.5khz at the input to the board and 1.27 volts output, having just zeroed on the least...
... John, is it possible that you have the more sensitive FGM-3h ? The FGM-3h can only be used in E-W direction - otherwise the sensor gets saturated... Best...
Hi Richard, At 145 kHz, the sensor is saturated. Is there ferrous metal nearby? This may sound like a stupid question, but I have to ask. Someone phoned me...
Hi Richard, An other factor sometimes taken for granted is that the sensor must be horizontal. That is, with the long axis of the sensor parallel to the...
No, it is an FGM-3 and this is movement with it already alligned in an E-W direction. jn ... +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ ... ...
Hello All I have definitly have the standard FGM-3. It is mounted horizontaly at all times. Right now it is on a wooden table about .7 meters from a concrete...
Hi Richard, Even though the frequencies seem higher than I've measured, the fact that there was a 2 to 1 change in frequency as you rotated it is a good sign....
... Hello Erich You were correct on a possible counter error. I checked with a scope and the square waveform is hardly symmetrical and that is probably causing...
Richard, I’m replying to your comment: ... Since it is on a long cable, I tried it outdoors on the same table at least 2 meters from any kind of metal with...
Hi All, Charles has a good idea. The FGM-3 output impedance is around 300 ohms +/- 100 ohms. My sensors are over 100 feet from the house, and I terminated the...
... Hello All I have a 78L05 at the sensor with suggested caps when I built the system. The termination sounds like a good fix. I wll try it and let you know. ...
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