fluxgate magnetometer

Hi,

Using a folding propeller (to reduce windmilling torque) and if necessary a 3phase shunt to short out the motor windings might work.

cheers, Jamie

Hi,

I saw it before but cool project Jan :) What's resolution in microTesla do you think you can detect? I guess there is somewhat shielding on most brushless outrunners from the metal case for return flux, if not enough a bit more could maybe be added, and then it would look just like a small chunk of iron 4 feet away, for the 8foot wingspan glider I'm looking at. I guess that static DC field could be cancelled out.

cheers, Jamie

Cool thanks for the info!

cheers, Jamie

On a sunny day (Sat, 22 Nov 2014 16:04:46 -0800) it happened Jamie M wrote in :

I really do not remember at this time the resolution. For me it was just 'try to get the idea of a fluxgate', a quick and dirty way to sample its output, and use as a compass. But it is affected by any iron around it, just like a normal compass. I think you can make a lot of gain if needed.

After that I bought an 'Compass pressure temperature sensor module DSPC01' on ebay: Calibrated digital sensor I2C data interface Pressure resolution: 0.01hpa

Pressure range: 300~1100hpa Altitude resolution: 1m Altitude range: -689~8948m

Standby current 2uA Supply voltage: 2.4~3.6V

Very small board, for in my laser arrow drone. I have written a driver for that board in C, if you need it, it is somewhere on my site. That board is slow, one measurement per second, but OK for heading. Not for altitude... One thing planned is perhaps when the AD oscillator board comes, in a 4 GHz altitude radar. :-)

If you really want earth magnetic field logging, I think those sensors that my website links too are perhaps more suitable, but I have not tried those:

Those are saturating core oscillators AFAIK. Tried to make one myself, but needs the right kind of iron I think, it worked, but not very sensitive.

For at sea I have this:

Note the compensation magnets, you can see the one in front with adjustment screw near bottom center. Fluid type, 12 V backlight, The real stuff!

You never heard of leaving the output at shorted stated in the bridge?

They call it dynamic braking and yes, the off state of the PWM does short the output to a degree, that is, if you really do have a real bridge in play.

Jamie

Something like nrad orientation information is needed to deal with the earth's field.

Best regards, Spehro Pefhany