What Is An Earth Inductor Compass? (4K)

[@tsbrownie]

Now I'm wondering if I could make an Earth inductor compass from 2 of those little tiny motors inside of cell phones....

[@denverbraughler3948]

The rotor of the generator must be isolated from competing magnetic fields. At that scale, there’s too much competition.

[@tsbrownie]

@@denverbraughler3948 I made and it works, but it works badly. The problem is not the decreased amperage (it's 1/10th the big one), but that the rotor has only 3 arms, so it's "resolution" is awful. I'm trying to make a video on it, but am struggling with the visuals. I need a tiny motor with 4+ arms on the rotor. Can't find one....

[@mariofachinsky5639]

Beautiful!. Im a commercial pilot and electronics technician, so this experiment is double interesting to me. Thanks for sharing & greetings from Argentina

[@tsbrownie]

Thank you. I used to fly and have always been fascinated by flying so this was something I had to try for myself.

[@jagmarc]

If you amplify the current from the brushes (i.e. into an opamp's inputs and using its +/- output swing) that can drive a geared-down motor to turn the entire assembly to find and maintain null by itself.

[@garyplewa9277]

In the Jimmy Stewart movie "The Spirit of St. Louis" they showed an Inductor Compass in his plane, spinning vertically by way of a 3 cup anemometer protruding out of the roof of the cockpit. It iced up during the flight and stopped turning. At that point Stewart said he was unable to tell if he was going in the right direction. That struck me as odd and I just wrote it off as made up Hollywood drama. Now I understand that this was indeed a real device and your demo in this video was a great illustration of it in action. Thank you.

[@michaellitzkow8123]

There is a very good replica of the Spirit of Saint Louis in the EAA museum at Oshkosh. When I toured it, the docent pointed out the earth inductor compass and explained its usefulness.That was 40 years ago, and it was the first time I ever heard of one. This video is the second time. It's not a well-known thing, but very cool.

[@JanetGrech]

​​@@garyplewa9277 Don't forget Lindy's actual book of the same name. He used a Mercator map to plot his course over the Atlantic in segments, then adjusted his course on an hourly basis, accounting for airspeed and estimated drift using Dead Reckoning. In the movie Stewart says there's nothing wrong with the method, except it's name. I've always wondered just how useful his Pioneer earth inductor compass was to help lighten the tremendous loaded effort flying the Spirit required to stay airborne. He had no forward view and became tremendously fatigued during the night hours over the Atlantic. He had the glass taken out of the side windows so he could stay awake due to the cold air from the slipstream hitting his face. The Spirit was built with some measure of aerodynamic instability that required good ear balance to help counter, so God only knows what the dangers of adverse yaw were in that plane. All in all, the earth inductor and his magnetic compass were life savers. His magnetic compass would have been drifting occasionally, but that rock steady needle on his Pioneer compass would have helped enormously to maintain his current heading. Also, when the Pioneer appeared not to be working would have been a good indicator how iced up the Spirit was at the time. Personally, that incredible flight is no different to going over Niagara Falls in a barrel, except he had his earth inductor to help point the way when his own senses were all screwed up.

[@JuhaLaiho]

Very interesting, and the vertical axle direction took me by a surprise, but I managed to get it - rotating the frame changes contact points of the collector brushes, so we're getting readings in different directions of the magnetic field. However, as this device likewise measures the actual magnetic field, it'll have the same troubles as a regular magnetic compass in the sense that if you looked at the readings of this device when located somewhere between the magnetic and geographic north poles, the readings would be 180 degrees off (in the geographic sense - the readings of this device would indicate north being in the direction of geographic south). Likewise the dipping effect (magnetic inclination) you mentioned for magnetic compasses affects this device just as well, and I think that is the reason your values are not symmetrical - the magnitudes of "north" and "south" indications differ in absolute values. I suppose you could find some off-vertical tilt angle of the axle that would produce equal values for the "north" and "south" indications, and I think this should also produce highest "north"/"south" values you'll be able to get the measurement to display. But definitely an interesting way to make an electromagnetic compass. Thanks for sharing!

[@jeffreystroman2811]

There is an abundance of gifted and generous commentary here, that has me more intrigued than the compass itself, of which I had to click upon seeing a dvm and two armatures

[@geor664]

Great video. Clever idea. 1) use an analogue Voltmeter rather than a DVM. the analogue metet needle will smooth out any jitter in your readings. 2) put two soft iron poles (a couple of soft iron bolts will do, one on either side of the rotor) across the sensing rotor. This will concentrate / focus the magnetic field being picked up. It should give you higher directivity gain. 3) you can quantify the directivity gain using the standard 2D DI (Directivity Index) using the standard DI formula (simple). Do the calculations using an excel spreadsheet. Look up Wikipedia for the formula.

[@tsbrownie]

Thanks for the great suggestions. I'll have to try it out.

[@Tassie-Devil]

Fascinating concept... but I'm missing something (probably obvious): Until you gave the demonstration, I assumed that the pickup rotor would be horizontal in use, with the long axis (ie the axel) pointing as you would a magnetic compass. What I don't get is how the reading when the rotor is rotating on a vertical axis... can vary when you rotate the entire device... around the same vertical axis??? I would have assumed that any stationary/fixed magnetic field lines would induct equally in the spinning armature windings whenever you rotate the device around the same axis.

[@tsbrownie]

You can find the original patents online for details. The Spirit of St. Louis used it on its transoceanic flight, and it was used by ships for a time. It does work horizontally (as I originally assumed it would work), but it's much less sensitive. I had to go back to the original drawings to see that I was wrong about its horizontal operation. To understand what it is doing, you have to think about the brushes and contacts. How they are turning on and off at specific intervals. Then it will make more sense.

[@tsbrownie]

Since I'm not a PhD in physics, I asked chatgpt for an explanation, and as I suspected it requires multivariant calculus to describe: Key Components: Induction Coil: The core of the instrument is a rotating coil of wire mounted in a gimbal, allowing it to move freely. Magnetic Field Interaction: The Earth's magnetic field acts as the "source" field. Working Principle: Rotation of the Coil: The coil is rotated at a constant speed within the Earth's magnetic field, either by hand or using a motor. As the coil rotates, the changing angle between the coil and the Earth's magnetic field lines induces an electric current in the wire, in accordance with Faraday's Law of Electromagnetic Induction. Current Strength and Direction: The strength and direction of the induced current vary with the orientation of the coil relative to the magnetic field. The induced voltage is at its maximum when the plane of the coil is perpendicular to the Earth's magnetic field (aligned with the magnetic meridian) and decreases to zero when the plane is parallel to the field (aligned with east-west). Directional Information: A sensitive galvanometer (or other voltage measuring device) is used to measure the strength of the induced current. As the coil is rotated, the point of maximum induced current identifies when the plane of the coil is aligned with the magnetic meridian, i.e., the north-south line. The direction can then be determined based on the way the instrument is oriented and the direction of rotation. Orientation to Cardinal Directions: When the induced current is at its peak, the instrument indicates that the coil is aligned along the north-south axis. By using the known rotation direction and interpreting the current peaks, you can determine whether you are facing north or south. For east-west directions, the instrument relies on the absence of a significant induced current when the coil is parallel to the magnetic field. Summary of Direction Indication: North-South Alignment: Maximum current is induced when the coil is aligned with the Earth's magnetic meridian (north-south). East-West Alignment: No current is induced when the coil is aligned perpendicular to the Earth's magnetic meridian (east-west). Advantages and Use: You said: I need a physicist-level explanation of how the coil is interacting with the earth's magnetic field because the coil is flat to the earth. It is operated, yeah, and it's not horizontal to the earth's field. It is being rotated. The four parts of the coil are flat to the surface of the earth. ChatGPT said: You're right to point out that in the earth inductor compass, the coil is often oriented flat (parallel to the Earth's surface) during operation. To fully understand how the coil interacts with the Earth's magnetic field when it is not horizontally aligned, we need to break this down into some fundamental concepts from electromagnetism. Earth's Magnetic Field and Its Orientation: The Earth's magnetic field isn't perfectly horizontal at most locations. Instead, it forms an angle relative to the horizontal surface called the magnetic inclination or dip angle. This angle varies depending on your geographic location: near the equator, the field is almost horizontal, while near the poles, it points steeply downward (or upward in the Southern Hemisphere). Key Concept: Faraday’s Law of Induction Faraday’s Law of Induction states that a changing magnetic flux through a loop induces an electromotive force (EMF) proportional to the rate of change of the flux: E=−dΦdt E=−dtdΦ​ where EE is the induced EMF, and ΦΦ is the magnetic flux through the coil. Magnetic flux ΦΦ is given by: Φ=B⋅A⋅cos⁡(θ) Φ=B⋅A⋅cos(θ) where: BB is the magnetic field strength, AA is the area of the coil, θθ is the angle between the magnetic field and the normal (perpendicular) to the coil’s surface. Coil Orientation: When the coil is flat and parallel to the Earth’s surface, the normal to the coil’s surface is vertical. However, the Earth's magnetic field is not strictly vertical. It is at an angle (the dip angle), so there’s still a component of the Earth's magnetic field that interacts with the coil. As the coil rotates, the angle θθ between the Earth's magnetic field vector and the normal of the coil changes periodically. This changing angle causes a variation in the magnetic flux passing through the coil, which leads to the generation of an alternating EMF as per Faraday’s Law. Understanding the Coil's Interaction with Earth's Field: Let’s break this down step-by-step: Initial Alignment: When the coil is lying flat on the Earth’s surface (say, parallel to the ground), the magnetic field lines are angled due to the dip of the Earth's magnetic field. The coil's normal vector will make an angle with the field vector. At this initial orientation, there is some initial magnetic flux passing through the coil. Rotation and Changing Flux: As the coil rotates about an axis parallel to the surface of the Earth, the angle θθ between the coil's normal and the magnetic field vector changes continuously. Specifically: When the normal of the coil aligns with the magnetic field (let’s assume when the coil is in the north-south orientation), θ=0∘θ=0∘ or θ=180∘θ=180∘, and the magnetic flux is maximized. As the coil continues to rotate to an east-west orientation, θ=90∘θ=90∘, and the magnetic flux through the coil becomes zero (since the magnetic field lines are parallel to the coil and no field lines pass through it). The periodic change in the magnetic flux during the rotation induces an alternating current in the coil, where the magnitude of the induced EMF is largest when the coil is aligned along the magnetic north-south direction. Induced EMF: As the coil rotates, the variation in the angle θθ modulates the magnetic flux and hence induces an alternating EMF. The maximum EMF is generated when the coil's plane is perpendicular to the magnetic field vector, which happens when the coil’s plane is along the north-south axis. Why the Coil Being Flat to the Earth Still Works: Even though the coil is flat to the Earth’s surface, the Earth's magnetic field has both horizontal and vertical components (due to the magnetic dip). Therefore, a component of the Earth’s magnetic field still penetrates the coil, even when it is flat. The rotating motion continually changes the orientation of the coil relative to the Earth’s magnetic field, producing a varying magnetic flux, which generates the EMF. Simplified Visualization: Imagine you’re holding a bicycle wheel (the coil) flat in front of you, and the Earth's magnetic field is like invisible arrows pointing at an angle into the ground (depending on your latitude). As you spin the wheel, the orientation of the wheel’s spokes (which represent the magnetic flux area) with respect to those arrows constantly changes. The stronger the alignment with those arrows (north-south), the greater the interaction and induced current. Thus, the coil, even when flat to the Earth's surface, effectively interacts with the magnetic field by constantly rotating and changing its angle relative to the Earth's magnetic vector.

[@JanetGrech]

So, a no-go without Maxwell's Equations, upon whose edifice, there would have been no 20th Century, as such!

[@tsbrownie]

@@DonnieLuve Thanks, but as much as I'd like to take credit and proclaim myself a genius, I'm just copying 100+ year old tech!

[@tsbrownie]

@@DonnieLuve You could clip the leads. I desolder 1 leg at a time, holding the soldering iron tip to the leg where it enters the board.

[@tsbrownie]

@DonnieLuve Maybe a higher wattage soldering iron is needed. Also, sometimes the leads are twisted and need to be untwisted.

[@adnacraigo6590]

I had never heard of this experiment before but I find it very interesting, perfectly understandable, and well executed on your part. I have seen an exprriment on youtube where a man reoved the magnets from a universal motor (a cordless drill) , switched it on and it ran when he brought a neodymium iron boron supermagnet(n52) within 15 feet or so of it.

[@tsbrownie]

@adnacraigo6590 If you google "earth inductor compass" you can find information on the one used in The Spirit of St. Louis. The original patent filings are out there too.

[@charleslaing3426]

A version of this instrument and a clock were the navigation tools Lindberg used to cross the Atlantic. His rotor was spun be a small windmill and his meter was an analog certer-reading one. He set the desired direction by rotating the brushes. The meter read zero when he was on-course and left or right when he was left or right of the desired heading. His route had pre-programmed magnetic directions for given periods of time. A regular compass is unstble in turbulece as well as suffering the magnetic dip effect.

[@tsbrownie]

I didn't know that, thanks!

[@Hopeless_and_Forlorn]

Nice demonstration, but as others have commented, in an airplane the Earth inductor compass cannot reduce errors due to magnetic variation or magnetic deviation, because the Earth inductor and the magnetic compass, whether needle or card, each sense the same magnetic "lines of force." In stable flight, an inductor will indicate the same magnetic heading as a simple magnetic card compass. Its advantages lie in the fact that it can generate a relatively robust, electrical heading signal, while a card compass is operated only by the interaction of small, permanent magnets with the Earth's relatively weak magnetic field. Also, the rotation of the shaft which spins the inductor assembly to generate the signal might provide some gyroscopic stability if the shaft is properly gimbaled. Even after the later development of flux valves, or flux gates, which use an ac coil to magnetically move the Earth's flux rapidly in and out of saturable sensing coils in order to generate heading signals with no moving parts, the problems of magnetic dip, variation, and instability persisted. The sensing element of the flux valve was gimbaled, again, to allow leveling of the sensor by gravity, regardless of the exact orientation of the case due to its mounting, for instance in a wing with dihedral. The gimbaled sensor was still affected by acceleration forces in flight, and any motion of the sensor from plumb resulted in unstable indications. Many of these problems were overcome with the addition of a stabilizing, directional gyroscope to the system. After WWII, most transport category aircraft had gyro-stabilized, flux valve based compass systems, many with multiple heading indicators in the cockpit or navigator's station. Although mostly stable, even in turbulent flight conditions, and even with compensators to counter the effects of deviation due to aircraft structure and systems near the flux valves, the indications they produced were still subject to the same problems of magnetic variation which affected the simple, magnetic "whiskey" compass installed in the cockpit as backup to the electronically operated gyro compasses. Finally, around 1980, inertial navigation units began appearing in new airliners, and these did away with magnetic compasses altogether--except for the backup whiskey compass, of course. Inertial units sense true heading rather than magnetic while the aircraft is stationary on the ground, and update heading by gyroscopic and accelerometer sensing and computation throughout flight. Although magnetic heading display continues to be primary on flight instruments, these values are actually derived from true heading and automatically corrected for local variation by reference to data in computer memory. Problems solved.

[@bachtube11]

Good information!. I have to ad only one information: Zero crossong point of the sine curve is a more exact point to head on, than the maximum of the sine wave, just offset the cale by 90 degree and you have exact reading ;-) If you plot the voltage output from the Earth Inductor Compass over angle you get a sine curve! If you want to find the exact north direction you would have trouble to find the exact angle for the maximum, as the voltage does not change much on the maximum of a sine curve. But the voltage changes much at the east or west direction, where it crosses the zero line of voltage. So the best use is to find the point of zero voltage, for example heading west, where you get good reaction on deviation from this angle. Lets say positve voltage if you deviate to the right and negative voltage is you deviate to the left. Charles Lindbergh heading to the west would get good indication of deviation of his heading direction if he used the zero crossing point of his Earth Inductor Compass. I guess all Earth Inductor Compass used this increased acuracy by using the zero crossing point and just offset the reading of the degree scale by 90 degree to get the correct reading to north. Lindberg had to follow a cours that was not always exact west, but adjusting an offset on the scale would do the trick, In praxis pilots had a adjustable scale offset, to find any heading anle they want to go to, and they could read just the positve or negative voltage while correcting theyr flight direction in order to hold the voltmeter needle to zero.

[@charlesnelson619]

You can also put the drive motor in a concentric magnetic shield or two. I was able to get (earths field) shielding w. 3 layer shield down to microgauss using mu metal ! Your setup is only sensitive to horizontal component of earths field when vertical.

[@chrisidema]

Make two of these 90 degrees apart and you get a vector output.

[@baruchben-david4196]

I'm not seeing how this would help with the problem of the north magnetic pole not being on the actual north pole. Seems to me that it would point in the same direction as a conventional compass.

[@michaellitzkow8123]

There are multiple problems with magnetic compasses on airplanes. First, it bounces around in turbulence and is hard to read accurately - the same is true on a ship. However, on an airplane things are worse because banking and accelerating the plane forward and backward all change the level line created by the liquid in the compass and then the vertical component of the earth's magnetic field near the poles has strong effects on which way the compas points. These instabilities are a major problem for pilots of small planes, even today. Those pilots use a gyro-compass to get around the problems, but still need the magnetic compass to calibrate the gyro compass periodicallly. The earth inductor compass gets around the stability problems, but doesn't alter the fact that magnetic north isn't generally true north. Still a stable reference to magnetic north is a beautiful thing in an airplane.

[@tsbrownie]

I agree with everything you said. My only "however" is, as I recall, the inventors claimed it was less susceptible to variance. I have not figured out why they said that, but their model also had multiple rotors and mixed the signals to get a final output. Mine is the most basic device to test their principle, so.... I need to find those diagrams and put some effort in to trying to understand how that might work.

[@ddegn]

A conventional compass can be pulled down to the point it no longer rotates freely. Of course most good compasses shouldn't get bogged down but I could see this being a problem with older compasses.

[@JoseSilveira-newhandleforYT]

Very interesting little project! At first glance, I was puzzled why use it vertical, as horizontal made more "gut sense" to me, as I didn't mentally account for the commutator in the armature - now it makes perfect sense :-)

[@tsbrownie]

@@JoseSilveira-newhandleforYT I know what you mean, I had to go through that same change of thinking. Learning reshapes the brain, sometimes painfully. 😁

[@JoseSilveira-newhandleforYT]

@@tsbrownie Yep, very true 🙂

[@user-rs8zg8ey2b]

Good video! The more poles the motor has, the more accurate pointing, same with slimming the brushes down will also help (less overlap), and more turns on each pole, I think I need to try this :)

[@tsbrownie]

Actually, you just figured out the video I'm working on, but there's a twist!

[@user-rs8zg8ey2b]

@@tsbrownie awesome, cant wait!

[@user-rs8zg8ey2b]

@@tsbrownie I wonder how a skewed armature stack (as some servo motors use) would affect this?

[@tsbrownie]

@@user-rs8zg8ey2b You want to be able to control which arms of the rotor are active because as you know, that's how the direction is determined, relative to them.

[@user-rs8zg8ey2b]

@@tsbrownie I was thinking a broken Dremel tool would make a good candidate, about 12 poles, larger (more copper) and large comm (gives more space).

[@sundaramguruswamy5490]

This electrical working principle function.Self adjusted poles.

[@rksg2003]

Hey man I knew you get this going! It work’s flawless. I’m going to attempt to build one for a true magnetic north experiment. Thanks for the video!

[@tsbrownie]

@rksg2003 You are welcome. I thought the first one was going to work. Broke my brain when it under-performed. Let me know if you have questions.

[@jagmarc]

See also Hall effect sensor and Fluxgate compass.

[@eduardoperes4428]

That was genius! Very interesting. An "electromechanical compass" Congrats.

[@tsbrownie]

It is interesting, isn't it? I have never seen one of these before!

[@ParedCheese]

Great video. 👍 Didn't realise such things existed. Seems like the sort of experiment that calls for an analogue meter. It just seems more fitting, for some reason. 😁

[@tsbrownie]

@ParedCheese You're the second guy to say that and I agree. I tried to find one online and in my junk boxes, but no luck.

[@DaveEtchells]

Fascinating experiment, something that makes perfect sense but I’d never thought of before. For a microamp meter, any 20,000 ohms/volt multimeter will have a 50uA meter movement. IIRC, 20K ohms/volt was standard for better grades of analog DMMs back in the day, so there should be plenty of them on eBay, easier to find than just a naked panel meter of that sensitivity.

[@jagmarc]

Or feed into an earphone and listen.

[@hooks2998]

Ideally you would want a center zero µA meter.

[@jagmarc]

@@hooks2998 or even more ideal inv/non-inv inputs Comparator.

[@jagmarc]

@@hooks2998 or feed them into comparator or differential amp inputs.

[@JordaoDM]

Amazing! Never heard of it before but it makes total sense.

[@tsbrownie]

I had always thought that thing on the Spirit of St. Louis was for measuring wind speed, then when I found it was a compass I had to see how it worked.

[@markg1051]

Nice experiment, thank you! Learned something new and useful today.👍

[@tsbrownie]

Glad you liked it. It also taught me a lot.

[@hu5116]

A physicist here. I was going to throw the BS flag (and in a way still am) until I read a comment about the orientation of the commutator brushes playing into the operation. My BS flag was going to be thrown under the assumption of motor symmetry, in which case this would never work. However, if one has only (for example) two brushes, diametrically opposed, and fixed to the chassis, then yes I then see how this can work. But one needs to point out this is specific to a particular type of motor. If you had any other type of motor it would at least not work as well, and likely not at all. Devil is always in the details. What is missing from this experiment is a test laying chassis flat and rotating it. When the motor is perpendicular to the field it should generate more voltage than when it’s parallel to the field, although now that you have shown axial coupling sensitivity one might have to also roll the chassis to get get max signal. It would have been nice to mention these sensitivities in the video, but regardless, good job, great video, thanks, and I learned something! Of course I think it will still be more convenient to pull out my iPhone ;-)

[@tsbrownie]

The video I took down showed it horizontally and vertically. That's part of the reason I took it down, because the photo I was working from showed it in the vertical configuration. There's not enough data online to try to recreate the inventors' thought processes/research; it's posted as old tech that's interesting and easily demonstrable. But you don't have to take my word for it, the frame 3D printer files are online, the motors are standard sizes and cheap. Go for it.

[@garydargan6]

So if you reverse the connections on the electric motor and it rotates in the opposite direction north will be +ve maximum and sout will be -ve minimum.

[@tsbrownie]

@@garydargan6 Yes.

[@neiloT.]

All the text book aside when the coil is vertical take away the mounting.. How do u measure the coil direction north south as it is spinning around the same plane.

[@tsbrownie]

It is relative to the brushes. The orientation of the brushes determines which of the rotor's arms are active. As the active arms best align with the Earth's magnetic field, the current maxes out.

[@knoxpruett1889]

Very nice experiment! I love the way it precisely lndicates NEWS directions the way it should.

[@tsbrownie]

@@knoxpruett1889 It surprised me how well it works given how basic the model is. Seems like there is a lot of forgotten tech that is the foundation on which current "magical" tech is built.

[@sundaramguruswamy5490]

Good for grid stability.and real theory coming to picture.

[@sundaramguruswamy5490]

Earth rotating RPM if matches any thing will happen?

[@tsbrownie]

The Earth rotates 1 time in 24 hours. It would basically be stationary and a stationary rotor won't produce an effect.

[@badabing7820]

Now the question: do you get some amps? And will it slow down, if you use the electricity.

[@tsbrownie]

@@badabing7820 I am measuring the microamps.

[@djmips]

What about a wind up clockwork version. Would that perhaps have less magnetic field interference?

[@tsbrownie]

Yes, but one would still have to have some space to keep the spring away. The originals were used in ships and planes. The ones in planes used windflow to turn the shaft. You can see it in pictures of the Spirit of St. Louis.

[@Da5idc]

If this uses the earth's magnetic field, how does it overcome the problem with the magnetised needle in a compass? I will work well away from the geometric North Pole, but it would have to be tested up north to show that it is better than a compass

[@jagmarc]

Doesn't have a swingy-round needle that tips ever further downwards the further you get to the Pole.

[@soilsurvivor]

Very cool! A bit more discussion about what numbers you'd expect before the demonstration might be useful. Depends on how much you want to get into the physics of what's going on. Cheers!

[@tsbrownie]

@soilsurvivor The actual devices went from a bit more complex to a lot more complex. Some had multiple coils in different orientations and the signals were mixed to give a left/right heading to destination. The readings depend on the coil (turns, size, core...), the speed it is spun, etc. It's a generator operating on a 3 dimensional magnetic field.

[@aayush_deo_ranchi]

It is good and a novel way to find direction. My friend better make a hand cranked one as if you are in a situation where you need a compua it ia highly unlikely that you will find a lab bench powersupply and a multimeter to drive and read the emf respecivtely. a dail made of leds only to keep it simple.

[@TheRealFreznoBob]

If the earth was making the magnetic field then I would imagine that the field would rotate along with any unevenness in the field due to uneven production of the field but since it doesn't I assume the field is created by a large current entering at the poles and thus unaffected by the spin of the planet.

[@iviewthetube]

Could you not also find the vertical component of the Earth's magnetic field with that device?

[@tsbrownie]

@iviewthetube I would think so. There's a thing called a dip meter and this should be able to do the same assuming the other magnetic components are not overpowering.

[@ЛеонидХаритонов-х6е]

С помощью этого прибора можно искать точки Хартмана. Узлы имеют разную полярность как и стенки. Good luck!

[@tsbrownie]

"Using this device you can search for Hartmann points. The nodes have different polarities, just like the walls."

[@neiloT.]

Stand it vertical and tilt in the different directions. That makes more sense to me. I'm trying.

[@tsbrownie]

The actual device was on gimbals to keep it flat to the Earth. Changing the orientation would make the readings inconsistent.

[@jamesmorton7881]

Ah i am interested. Good. ❤❤. Knowledge is Power. Thank you.

[@Georgy-11811]

I think it should work to some extent even if the whole device lying on the table will rotate horizontally, perpendicular to the axis of the rotor. I wonder if this is true.

[@tsbrownie]

I tried it and it does produce electricity, but it did not work as well.

[@Georgy-11811]

@@tsbrownie It might help to try to find a suitable commutator position offset by rotating the device around the axis of rotation. After all, change the position of the commutator in relation to the direction of the magnetic field is actually the principle of the device.

[@tsbrownie]

@Georgy-fg3bg The brush plate has a key that fits into a slot on the frame. That was by plan. If you built from my plan it would have the same results.

[@Georgy-11811]

@@tsbrownie Of course, it will work best in a vertical position. The device works like a regular dynamo with a permanent magnet stator. In this case, however, the magnetic field of the stator is represented by the magnetic field of the Earth. The problem with this compass is that it shows the same values ​​twice when turned 360°. (they repeat after 180°). We find the direction to the pole, but we are unable to determine whether it is north or south.

[@tsbrownie]

@Georgy-fg3bg The actual devices used multiple rotors in different orientations. Later ones just showed if you were left or right of your target heading.

[@franzliszt3195]

Does the rotor have any magnets?

[@tsbrownie]

​@@franzliszt3195 No, it's just the rotor, bearings, and brushes from a DC motor. The only magnetic field should be the Earth's.

[@franzliszt3195]

@@tsbrownie well this is rather interesting.

[@dougaltolan3017]

I don't see how this wouldn't be susceptible to declination? Inclination : sure but with reduced sensitivity as you approach the magnetic north pole.

[@tsbrownie]

@dougaltolan3017 I don't either, unless it was dynamically adjustable. The actual device had multiple rotors, so they may have found a trick that I am not seeing. I'm just going off their claims, which overall seem to be correct. It's a matter of trust until I can prove it one way or the other.

[@dougaltolan3017]

@@tsbrownie Who is "they"? I'd like to see all of thier work please.

[@tsbrownie]

@dougaltolan3017 If you google "earth inductor compass" the original patents show up in the results.

[@Fred_Klingon]

Hi, this is great, it's the first time I see such device. Do you need a minimum size for the motors? I guess that using smaller motors makes the reading more difficult. I guess that the two motors should stay at a certain distance to avoid interferences. If that's the case, would mounting one motor at a 90° angle reduce them?

[@tsbrownie]

Bigger motor / more windings = more electricity. Yes, the first one failed because the motor was too close (I deleted that video). I'm not sure if mounting it 90 degrees would help, I think probably. It's easier / cheaper just to separate them by 10 cm.

[@Fred_Klingon]

Yes your design is definitely easier. I was thinking about how small this device can be built 🙂 in fact a 90° version would require only a cardan joint (I hope the translation makes sense), probably it can be 3D printed as well. Another design could use a belt and two gears (horizontal axis, one motor facing ↓ and one ↑, like in the video)

[@tsbrownie]

@@Fred_Klingon I remade the device using 2 very small motors, but it does not work right. I am making a video on why, and it's mostly due to the fact that the smaller motors have only 3 arms on the rotor, something I missed until I was almost done. I'm going to try to finish it to help show how it works and why it needs 4+ arms. Having trouble with decent graphics to depict what's going on. It gets confusing without being able to see it.

[@Fred_Klingon]

Nice! I'll watch the video once it is ready

[@Wink_Dinkerson]

I never, ever thought of that.

[@tsbrownie]

@@Wink_Dinkerson Me either. I saw it on the Spirit of St. Louis and started searching.

[@daviddavidson2357]

Is this just designed to stop the compass needle dragging, as I'd imagine declanation is still an issue with it.

[@tuttebelleke]

Was thinking the same. And one could incline the classic compass to compensate for the field inclination and stop the needle dragging?

[@tsbrownie]

As I recall, the inventors claimed it would remove variance, but they also were mixing signals from multiple rotors. I need to find their diagrams and do some thinking on how that might work. Mine is just designed to see if/how well the basic principle works.

[@daviddavidson2357]

@@tsbrownie Thanks for the response. They could maybe be more accurate if stuff like declaration was done using a computer or analogue circuit and multiple compasses were used, it's an easy way to link compassss together reliably (I suppose the other way would be to make a compass into a potentiometer, or lead one into a pot, but friction would probably cause inaccuracies) so maybe this was one way to make a reliable compass with an electronic output.

[@VinceBearinger]

Very cool

[@debnath5110]

Nice idea....Thank you Sir....

[@bobs12andahalf2]

That is cool as a very cool thing 🔥

[@BowlingSuperior]

Nice job! Another experiment to supplement this one would be to take a long single wire where you are flowing a fixed current thru it, say 1/2 amp or so, from a current-limited power supply. This long wire will produce a magnetic field much greater than the earth's magnetic field. Place the wire alongside of the inductor compass and repeat this test - I would suspect that you will see a greater voltage induced. You can then change the geometry of this long wire with respect to the inductor compass to see the nulls and peaks. This is basically a repeat of the experiments that Faraday performed many years ago.

[@tsbrownie]

Interesting idea.

[@andyash5675]

Very nice indeed!😀

[@danboy3399]

That would look great connected to an analog microAmp meter

[@tsbrownie]

Funny you should say that, I've been trying to find one online. I might have to dig through my boxes of parts as a last resort.

[@jonathanseagraves8140]

Wow.... great video.

[@guillaumedupin9732]

As the earth magnetic field is not at his maximum in a vertical plane, I guess you should also be able to aproximate your latitude, indirectly of course, as the earth magnetic field is at his maximum neither horizontal nor vertical... Maybe by putting your device inside a gimbal like cage ?

[@tsbrownie]

Actually, the real device was on gimbals to hold the coils flat to the Earth.

[@thomaslindell5448]

That’s so cool.

[@jazzjohn2]

The only thing that's changing relative to the magnetic field is the frame of the device. The rotor is always rotating at a constant shaft angle (perpendicular) relative to the magnetic field and to the earth itself. Like others here said, it looks like it shouldn't work!

[@tsbrownie]

The patents and pictures of the device are online. Charles Lindbergh used it, so there's that. However what most people seem to miss is the Earth's field lines are not flat to the surface of the Earth. They are arcs. The actual device was on gimbals to hold it parallel to the Earth. A coil spinning in a 3D magnetic field (where the field lines dip through the coil) requires Faraday's calculations using multi variant calculus. See the pinned comment above.

[@garyplewa9277]

You are correct, the frame is rotating, but so is the brush holder and the contact points being made on the commutator. This is the key to the design. The maximum voltage produced in the coils of that armature will occur as they cut through the N - S lines of flux. When the brushes are moved, via the frame, to align with the commutator segments for those coils, we see the peaks, both positive and negative, on the meter. When the frame is rotated 90 degrees the brushes then make contact with the armature coils moving with the magnetic lines of flux (e.g. east & west) and little voltage is shown on the meter.

[@1943vermork]

Instead of turning the frame, he could just turn the brush holder and accomplish the same result. Pretty cool stuff. Never thought earth magnetic field could induce a current in such a small coil.

[@peterwright4224]

You need to realise it's the position of the carbon brushes you are seeing 0n 360°

[@jazzjohn2]

@peterwright4224 ahh... that makes sense since that's a part of the motor that's not rotating with the armature. The earth's field adds or subtracts from the field of the motor's permanent magnets.

[@FreemonSandlewould]

Uhhh. You are rotating about the axis of rotation of the motor. Can't you just wait a fraction of a turn and get the same thing? Something is wrong here.

[@tsbrownie]

@@FreemonSandlewould Think brushes. Only 2 arms of the rotor are active. The orientation of the brushes determines which arms are active and when.

[@neiloT.]

Sorry mate that won't fly​@@tsbrownie

[@markg1051]

@@neiloT. Of course it won't fly, it's a compas and not a bird or a plane.😎😁 What you are seeng here is a DC motor rotor removed from its magnet assembly and spun in the earth's magnetic field instead. Basically, the rotor doesn't care where the magnetic field comes from, it will generate (or not)an output depending on its orientation to the magnetic field. Also, in this setup, it doesn't matter whether the spinning rotor is horizontal or vertical at 90 degrees to the table top. This is evident in the video here at the point where the driving motor is initially powered up (where it's horizontal) and the amp-meter reads 30 something uA, and when it is moved vertically, the reading stays much the same (taking into account any positional differences relative to the earth's field caused by manual movement of the assembly). If you are still unsure of this, review some of the basic operating principles of brushed dc motor which I presume you are already familiar with to some eegree and know that it is both a motor and a generator, depending only on how it is driven - electrically or mechanically. Cheers.🍺

[@justinanderson267]

Hahahaha My dyslexic ass though this said "Earth Indicator Compass" and I'm thinking "Let me guess, it points down?"

[@tsbrownie]

@justinanderson267 You and me both. I had to redo the first part of the video because I kept saying earth indicator compass.

[@paradiselost9946]

the irony is that a compass needle DOES point down? "dip" meter...

[@neiloT.]

If earth's mag flux is strong enough to make this operate correctly why aren't all the powerful magnets on earth not facing in the same direction.

[@hooks2998]

Physics.

[@tsbrownie]

It is producing 30 micro amps or 0.000030 amps or 30/1000000. If I spin that motor with regular magnets it will produce more like 2.x amps. So the Earth's magnetic field has an effect that is 66,667 times less than the magnets the motor came with. If I hang a huge bar magnet on a string, it will align with the Earth's magnetic field. If I put a magnetized steel ship in a lake with no currents, it would try to align N S.

[@arsentel]

👌👌👌👌👍👍👍👍👍👍👍👍👍👍👍👍

[@neiloT.]

Talking of brushes they're only connecting the rotor winding to meter. I think that one is grasping for straws a little.

[@hooks2998]

Yes, but there are multiple windings around the rotor and only the windings with their commutator segments under the brushes are connected. If it was a slip ring rotor then no it would not work but this rotor has a commutator.

[@tsbrownie]

I started to make this a slip ring, then figured out it would not work as a compass.

[@tanner3801]

This should also work with a paramagnetic disk, similar to early DC power generators. One radial brush, and the shaft is the other electrode (you would need a brush for the rotating shaft). Perhaps it would work better than DC brushed motors with few poles and commutators. Unfortunately, precession may make it difficult to sweep it to find North 😅

[@tsbrownie]

@tanner3801 A continuous commutator contact will produce electricity, but won't work as a compass.

[@tanner3801]

@tsbrownie in terms of generating EMF proportional to the flux and direction of rotation, yes, I think it would. The angular velocity may need to be higher than this wound rotor (depending on the radius) and the rotational axis would be perpendicular to the above example... but it should behave similar in terms of angle:voltage. Am I missing something?

[@tsbrownie]

@tanner3801 The actual device and my model both have interrupted commutators. That way only 2 of the coils are detecting at a time. That gives good sensitivity to direction. If all the coils were detecting all the time the current would always be the same.

[@tanner3801]

@tsbrownie because each winding has different EMF at any given time while rotating and they would short out and give either the avg voltage or zero... but at any given angle (dictated by the brush locations) they should have roughly the same EMF, which is why you get a constant voltage aside from the commutator interruptions. A DC generator accomplishes exactly the same thing, except you have no definite interruptions between n winding due to the commutators. The EMF is generated the same way, except a wound motor has much higher inductance and would produce higher EMF per the same magnetic field. I do think it would work similarly.

[@tsbrownie]

@tanner3801 The original patents are online, you can read for yourself. These devices were used on ships and planes. It's not a matter of guessing.

[@donm1547]

I would suspect that if you were at the equator doing this experiment, your voltages would be EQUAL in either direction and still show positive and negative for Direction

[@tsbrownie]

@@donm1547 I think you're right because the Earth's field lInes would still run N S.

[@ApocalypticIdol]

That's interesting that you're spinning it that axis, I would think it would spin it's yaw axis.

[@tsbrownie]

Me too, but then I looked at the original pictures and diagrams.

[@DirkLarien]

Had the same thinking since the coil would be more aligned with the field when align flat. But that would be the case only if we were to test it somewhere around equator. What if it is the due to the shape of the field ? Mr Brownie where do you live ? It is most likely USA, but are you from northern part near Canada by any chance ? Cause if you do it could explain it.

[@willdodd1038]

I would suggest that your armature is being influenced by something other than the earth with its axis vertical orientation. Unless you are north or south of 60degeess N or S, the isogonic lines are running at close to 90% parallel with the earth’s surface and shouldn’t be reflecting a Change in output merely by moving your makeshift frame around the armature. To observe a change in this setup, it should reflect a change by moving the apparatuses nearer or farther the the earth’s surface. Besides think about WHAT you are doing by turning the frame’s “clocking position” in relation to the spinning armature, how are your movements any different to the earth than what the shaft is ALREADY DOING? Something else is causing the change in EMF, an NOT the earth’s magnetic field. Try suspending your experiment from a non magnetic TREE in the middle of an open plowed field, suspended by fishing line, on a swivel, spun up to high RPM with compressed , while having ZERO metal on your person, as you lift an empty gallon glass around it, with a static grounding wire attached to block any wind. We would really look foward to seeing it.

[@tsbrownie]

@@willdodd1038 You can find the original patents online and see photos of it. It was oriented vertically with the coils flat to the Earth's surface. The orientation is set by the brushes. It took me a while to get it also.