One of my current construction projects is a Magnetometer based on a kit from Speake & Co using their FGM-3 Magnetic Field Sensor.
The sensor detects changes in the Earth's magnetic field. This is changed into a DC analogue output which will vary dependent on changes to the Earth's magnetic field.
The sensor is very sensitive to local variations in the magnetic field and also to temperature.
I have tested the system before but always found temperature stability to be the main problem. With the new kit, I am aiming to reduce temperature change by separating the FGM-3 sensor from the main electronics by burying the sensor in box a few feet below surface level where hopefully temperature will be more stable.
I am also using an Arduino so I can have remote control of the sensitivity settings and the reset switch to make it much easier to manage the impact of any major magnetic or temperature changes.
The following picture shows the kit of parts as received, ready for assembly:
The kit is reasonably easy to construct and consists of the FGM-3 sensor and a small circuit board that hosts the electronics to take the output of the sensor and converting to the variable DC voltage.
No Surface Mount Devices so still within my soldering capabilities!
So far I have installed the sensor in the box that will be buried. This is shown in the picture below:
The box is a small waterproof box, in which I have installed a length of plastic cable trunking. This is perfect for holding the sensor which is secured with a couple of cable ties. The trunking will be glued to the sides of the box and the cable entry hole sealed ready for burying.
The cable is Ethernet Cat 5 which should work fine for this application. This will run back to the main box which houses the electronics.
Next stage is to construct the circuit board and test. I will update as the project progresses.
