Shearwater
Well-Known Member
..............is there a little man with a magnet inside my Raytheon ST1000 ? If not can you explain how it knows which way its pointing?
Fluxgate compass.....
- Thread starter Shearwater
- Start date
lpdsn
Well-Known Member
The older fluxgate compasses are basically just glorified fishing weights with a small PCB on top. The weight is gimbled.
The modern ones, such as the EV1 are apparently much more sophisticated using technology that has been developed for smart phones.
Lon nan Gruagach
Well-Known Member
Well, not exactly a little man but there is a magnet. The magnet is suspended so it can spin and there is a coil that can keep it line up with the case. There is also a sensor (usually optical) that triggers when the magnet is in particular orientation. Now then, the little man (a very simple electronic circuit) energises the coil just enough to trigger the sensor, the effort needed to do that gives a value that can be used to determine which way the magnet would point (North) if the coil was not energised.
William_H
Well-Known Member
At least one older kind of flux gate or flux valve compass uses a pair of coils on iron cores mounted at right angles to one another. Often gimballed to keep them aprrox level. Each coil is treaded separately. The coil is periodically (400hertz) energised to saturate the core then current is removed allowing the magnetic field to collapse in the core. The resultant current coming out of the coil with field collapsing is peculiar to the amount and direction of the earths magnetic field. ie aids or opposes the collapse to a measurable degree. Comparison of the wave shape of the 2 coils can give direction for the earht's magnetic field. A processor then operates a dial autopilot or in the case of aircraft slowly aligns a gyro card to give a gyro stabilised compass heading. That is one kind but often remote compasses just have a magnetic needle swinging on a card whose direction is detected optically.
More modern types might use "Hall Effect" semicondcutor sensors where conductivity is varied by applied magnetic field. A few of these set up for great sensitivity are likely used in tiny hand held devices.
good luck olewill
More modern types might use "Hall Effect" semicondcutor sensors where conductivity is varied by applied magnetic field. A few of these set up for great sensitivity are likely used in tiny hand held devices.
good luck olewill
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Ruffles
Well-Known Member
It's kind of amazing that they're still making them with olde worlde compasses in. Surely it would be cheaper for them to pop a smart phone compass onto a daughter board? And then when the 'o' rung fails and falls into the bottom of the case it wouldn't jam the compass.
Ric
Well-Known Member
GPS antennae are becoming so accurate and cheap now that better still would be a GPS compass such as this (http://www.panbo.com/archives/2014/...ps_compass_true_heading_comes_to_the_usa.html).
I might fit one once the prices come down a bit. Get rid of crappy magnetic bearings entirely
alant
Well-Known Member
Can you explain all that again, in really simple english pls.
adwuk
Well-Known Member
GPS antennae are becoming so accurate and cheap now that better still would be a GPS compass such as this (http://www.panbo.com/archives/2014/...ps_compass_true_heading_comes_to_the_usa.html).
I might fit one once the prices come down a bit. Get rid of crappy magnetic bearings entirely
Can these GPS based compasses provide an accurate rate of turn? I think one of the main advantages of a fluxgate compass is that, as well as heading, it provides rate of turn which is essential data for an autohelm.
SiteSurfer
Well-Known Member
I read that entire very technical text as "swingy metal thing which tells something where to point".
