Skates97 Posted March 25, 2019 Report Share Posted March 25, 2019 2 hours ago, MBDiagMan said: Uh oh! Paul is thinking. Seriously though, what can be considered a MAGNETIC direction finder other than a compass, either conventional or remote. I’m anxious to read what you come up with. All depends on what the definition of "is" is... Are we talking about a device that determines direction by using the magnetic field (compass) or something that determines your magnetic direction? Even under the first definition, I would think that a magnetometer would/should qualify as it measures magnetic forces, albeit with a sensor, to determine direction. Then again, I am not an old bureaucrat in the FAA... 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 26, 2019 Report Share Posted March 26, 2019 The card compass has a gear thrown in so that when you turn to the right the card goes the same way your are expecting... The original compasses are labeled backwards, appropriately, and can be confusing when using them at first, or all the time... As in you add a few degrees, when subtracting a few degrees gives you the right answer... Bottom line... the extra gear makes marauder’s compass turn the other way... Great accelerometer too! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted March 26, 2019 Report Share Posted March 26, 2019 8 hours ago, carusoam said: The card compass has a gear thrown in so that when you turn to the right the card goes the same way your are expecting... Can anyone point to a link showing the internals of a card compass? I find it to be a quasi-magical device and would like to know more about how it works. How can they connect a shaft to a magnet that produces enough torque to turn a shaft subject to the ridiculously weak strength of the Earth's magnetic field, all in a turbulent/vibrational frame? A whiskey compass I get. The card compass seems to good to be true. Like there must be some hidden wire importing electrons to run some kind of amplifier and stepper motor. 1 Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted March 26, 2019 Report Share Posted March 26, 2019 2 hours ago, Fred₂O said: Can anyone point to a link showing the internals of a card compass? I find it to be a quasi-magical device and would like to know more about how it works. How can they connect a shaft to a magnet that produces enough torque to turn a shaft subject to the ridiculously weak strength of the Earth's magnetic field, all in a turbulent/vibrational frame? A whiskey compass I get. The card compass seems to good to be true. Like there must be some hidden wire importing electrons to run some kind of amplifier and stepper motor. We had a card compass on our club Cherokee, and I remember thinking the first time I saw it "WTF??? What devilry is happening inside this infernal device?" 2 Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted March 26, 2019 Report Share Posted March 26, 2019 It would be mucho fun to take one apart and see what makes it tick. Anybody have an old non-working one they want to get sacrifice in the name of inquiry? I'd post photos of the disassembled unit. Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 26, 2019 Report Share Posted March 26, 2019 My memory was from a drawing from a Jepp IR course... They have a good section related to how common instruments work, and failure modes... this covers the operation oddities of the mag compass, very similar to normal, but with a twist... discussing the niceties of rotating the proper direction... http://www.flight-mechanic.com/compass-systems-the-vertical-card-magnetic-compass/ For those that always wanted, but didn’t need a mechanical engineering degree... check out the drawings in this patent. Note the 45° Beveled gear. https://patents.google.com/patent/US3875676 When it comes to strength of magnetic force.... the earth is quite large and rotates quite quickly.... So... adding that fancy gear, makes the card compass pretty nifty... Best regards, -a- 2 Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted March 26, 2019 Report Share Posted March 26, 2019 5 hours ago, carusoam said: For those that always wanted, but didn’t need a mechanical engineering degree... check out the drawings in this patent. Note the 45° Beveled gear. https://patents.google.com/patent/US3875676 Thanks Anthony! That is one of the best written patents I've ever read. Extremely easy to understand. No need to take one apart now. Still impressive- those jewel bearings are pretty darn low friction! 1 Quote Link to comment Share on other sites More sharing options...
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