Comparing Regular fluxgate (1 driving coil and 1 sensing coil = 2) and MagentoInductive (1 coil in oscillation), (using a magnet detection distance from the sensor of around 3 feet), I've come to the conclusion that Magnetoinductive is not as sensitive as fluxgate, which I'm assuming is because the core is not being driven into saturation with MagnetoInductive (it's low current).

Being that the field drops inversely proportionally to the square of the distance, initial testing indicates that MagnetoInductive is approximately 5-10 times less sensitive.

However MagnetoInductive would be fine for a low budget general compass. For the purposes of this project, sensitivity is a requirement.

Now for driving the fluxgate coil. For testing purposes I've been using a transistor oscillator (confusing as MagentoInductive uses an oscillator too), but this transistor oscillator uses both the sense and drive coils. Ultimately I want to migrate away to a microprocessor drive for accuracy reasons, and the output current of a typical microprocessor isn't enough....

To get the cleanest sense signal in a fluxgate, the drive should have it's field reversed on each cycle. I.E. 0V-5V, 5V-0V, 0V-5V, so I need a driver that can switch rails (similar to driving a DC motor forwards and backwards).

So, this evening I've designed and CNC'd (othermill) an H Bridge driver, driven by 1 pin (direction) and is complete with transient suppressors and schmidt triggers (although the transient suppressors I need to order so I'm chancing it for now). All driven by a teensy 3.1 rolling through a frequency spectrum 1KHz - 300KHz for testing purposes.

The PCB off the mill without components is above. The following is the PCB populated:

Testing the drive outputs (unloaded) to check correctness:

Connected to the coil and the Teensy:

Running at 10KHz, notice the flux collapse / recovery in the sense coil is text book:

Schematic for H-Bridge Driver: