3 Axis Earth's Magnetic Field Sensor

Brooke Clarke, 2002 - 2014




eBay words:  GeoMagnetic (EMR) Unit  This unit features a large conical yellow shell (possibly fiberglass or plastic).  The base of the shell has one main central bolt surrounded by a metal disc that features two bolts for attaching this unit to something else (I don't know what).  That disc with bolts is adjusted in height by 3 bolts that lead into the interior of the unit.  There is also one ten pin (male) connector threaded on the exterior base and two metal side plates (use unknown)   Interior of unit has three brown rods that that are set up directionally with each one facing a different way  These three rods are held in by a solid plastic base with plastic adjustable screws for easy removal of each.   There is multi-colored fine wiring connected to the two lower rods. Each rod reads: 35181-51079 with an arrow painted at one end.  I do not know what this unit does specifically but judging by the GEOMAG sticker, it must be related to magnetic studies somehow. If anyone out there knows what it is specifically used for, I'd love to know!!   It is untested but seems to be in very good condition in the interior with some scratches to the outer yellow housing. Very interesting unit!!

The eBay seller is in Canada and the letters EMR show up a lot in relation to Canadian web pages for the Earth's Magnetic field.
A Canadian company called CAE has a CAGE code of 35181 and may have made the sensor rods.

I've been told that the sense coils are also used in the AN/ASQ-504(V) made by CAE Canada.

Made by EDA of Canada, now out of business. Is a fluxgate type.

Upper frequency limit is 0.5 Hz.  It's designed to measure the static Earth's magnetic field, not rapid variations.

There were different model numbers, FM-100 and FM-105.  What's the difference? Let me know if you have a manual or other documentation.

EDA FM100B Fluxgate Magnatometer Controller

This may have been a parts unit to keep others running.  It's missing the latches for the aluminum case.  All the cables are missing.  The Timing PCB is missing and there are anotheer three slots for another set of Z, Y & X boards, but they are keyed so as to not accept the Z, Y & X boards that are installed.

The Z, Y & X cards have a paper sticker with 10,000 nT/V crossed out and below 5,000 nT/V added.  The loose capacitor came off the Z card.  It was soldered in parallel with a cap that is on the board.  The Y & X boards also have the added parallel cap (maybe related to the lower sensitivity?

                  Fluxgate Magnatometer Controller
                  Fluxgate Magnatometer Controller

Stepped Output: MS3102A-14S-2S(C)
Direct Output: MS3102A-14S-2S(C)
Head: MS3102A-14S-6S(C)
                  Fluxgate Magnatometer Controller
Boards (left to right)
Z: single axis from sensor
Y: single axis from sensor
X: single axis from sensor
OSC: to drive fluxgate sensors
REG:  (Regulator)
Tim: Missing (Timing ? Required for operation?)
Z, Y, X: missing (second sensor?may be an option)
Power Supply
loose parts: 2 fiber washers & cap. from Z card

                  Fluxgate Magnatometer Controller


Fluxgate Magnetometer
Model FM-100
manufactured by
EDA Electronics, LTD


Fluxgate Patents
Sensors - Magentic


http://www.ufoupdateslist.com/digest/DIGEST27.TXT - mentioned the 0.5 Hz upper freq limit.

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Page created 13 June 2002.