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The story behind
Magnetometer kit

The legendary FGM 3 magnetic field sensors and DIY gradiometer kit are back! Invented originally in early 90’s by the engineer Dr Noble in Wales UK, the FGM series of flux gate magnetometer sensors was distributed by the partner Bill Speake through his established company Speake & Co Llanfapley based in Abergavenny Monmouthsire, and regularly supplied to our company.
– Map of Wales
– Abergavenny in Monmouthsire

We took it one step further…

We have taken the time and efforts to update the Speake FGM sensor and magnetometer kit electronics board design in terms of quality, performance and constructional quality controls!

Speake sensors business closed…

Once Bill Speake passed away in 2017, Speake sensors business closed and our task became to continue serving the customers by providing the acclaimed do-it-yourself magnetometer kit.
– Bill Speake was also a keen hobbyist for vintage machinery engine design
FGM 3 PRO assembling the sensors electronics board and coil windings

Electronics boards 5

FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound

4Inside the process…

Pouring the potting compound into the FGM 3 PRO sensors and left to mature

FGM 3 PRO Sensor Cutout

Our product is not an FGM magnetometer sensor imitation like those you can find online from hidden providers! The new FGM 3 PRO type version sensor now has more sensitivity, gained primarily by using in our manufacture higher conductivity materials in the internal sensor structure.
– Sensor cutout

Photos from our ready made magnetometer kits

FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound

A walk inside the laboratory…

Apart from quality materials, once individual FGM 3 PRO magnetic field sensors are completed in our laboratory, they are tested by taking the time to run quality controls. The purpose is to prove the detection range with sample targets.

4Inside the process…

Pouring the potting compound into the FGM 3 PRO sensors and left to mature
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– Testing every new FGM 3 PRO sensor depth range and signal stability

Building a gradiometer kit…

Also, as 2 magnetic field sensors are required as a pair to build a gradiometer kit, their electric properties must be equally balanced for both sensors. In the original FGM sensor design and various web site offered FGM imitations the matching procedures for every pair were not implemented. We are dedicated to match every pair of magnetometer sensors produced so that their voltage outputs will be exactly the same.

Therefore the gradiometer kit you receive will only have to be adjusted by aligning the sensors (for canceling the earth magnetic field as you will read in the pdf), and not any interference signal occurs from a pair where one magnetic field sensor has a different signal output compared to the other. The sensor pair matching enables you to align the sensors easier and faster as it has minimized false magnetometer signal effects.

FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
speake_fgm_3_pro_balanced_gradiometer_sensors_pair

FGM 3 PRO gradiometer sensors are matched in pairs with equal electronic properties?

The signal output on every individual FGM 3 PRO sensor has been tested in our lab and marked by hand on its label. To construct a reliable gradiometer both sensors have to produce exactly the same signal output, otherwise noise and unstable operation occurs. The pair of gradiometer sensors you will receive has been selected so that both sensors are matched to produce exactly the same signal output. In other words, every pair has the same linearity, and the end result is great depth performance. The output of each sensor is marked outside and matches to the sensor that it has been paired with.

Positioning the sensors

In most cases what is left to be required from you, is to physically position the sensors in a 90-degree aluminum or plastic profile and you are ready with the gradiometer! The magnetometer kit electronics board is pre-assembled and also tested. The board includes an LCD that monitors each sensor readings with +/- polarity signs and numerical values, has a battery status meter and a timer for the initial startup sensor balancing. The target audio signal is a precise VCO with frequency output range 0-3000 Hz through a speaker.
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– Both sensors come as matched pair. Have been tested to produce exactly the same signal output as written in their label by our inspector technician.
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– New digital magnetometer kit board. At startup the processor balances the sensors and the LCD has a timer to inform the user when the process completes.
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– Magnetometer kit LCD displays negative or positive fluctuations of each sensor, also the total processed value of both and battery meter.
Rest assure that with our FGM-3 PRO sensors and magnetometer kit pcb you will build an instrument with performance that is found only in high priced commercial magnetometers.
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– Building the gradiometer. Sensors are aligned to each other into a right-angle aluminum or plastic profile
FGM 3 PRO magnetometer sensors electronics boards are assembled, positioned into their acrylic enclosure and ready for pouring the sealing potting compound
– Fine balancing mechanism for both sensors. Adjust it outdoors, for the lowest possible noise when the gradiometer assembly is rotated. Then seal it with glue.