Tablet as a field monitor?

Have anyone come across a tablet that would have a HDMI input? Or a hack to make one? I mean there are lots of 10" monitors but none of them have a screen as good as a cheap tablet.

Topic by DainiusG   |  last reply


Electromagnetic field generator

An electromagnetic field generator strong enough that can disturb the tv signal of your neighbour next door

Topic by SalemSnaKe   |  last reply


Unified field theory?

I was windering if someone could tell me how to add gravity to the Unified field theory? thanks

Question by RelyNupon   |  last reply


Linear Magnetic Field

I am stuck in my research,please tell me a way to make a linear electromagnetic field,other than making an outer core for it please help me

Topic by ajose4   |  last reply


Light field camera

Came across this interesting camera that fuses the images from multiple lenses. https://light.co/camera  I suppose it is a "light field camera" as described here https://en.wikipedia.org/wiki/Light-field_camera Any suggestions on possible solutions, or links to similar projects? Prefferable that uses lenses from disposed of smartphones. 

Topic by mskogly   |  last reply


Field of view of a lens?

Hunting through the attic I found an old 35mm projector. I wondered what governs the field of view of the lens system - for this projector it is obviously about the size of a 35 mm slide but for my video projector it must be considerable bigger although the lens looks similar. (I know hat isn't a very scientific judgement!)

Question by rickharris   |  last reply


Magnetic field redirection? Answered

Hi, I've never seen a community so welcoming and intuitive than the instructables community, so I decided this website is the best place to ask my question. I'm sure there is someone hidden deep within the fathoms of instructables that is versed in the matter of magnetic field redirection. I'm working on a project that I will post an 'ible of, (truly wireless speakers ;)) but I need some method of redirecting a magnetic field so it doesn't interfere with the speakers. I have heard of some methods, i.e. Mu metals, MagnetShield, but these are not easy to come by, especially in the UK. I have considered ordering from the manufacturer, but I am not willing to pay the exorbitant shipping costs. I would firstly like to know if such a material exists, or if alternative/better/cheaper methods are available, secondly, whether or not it can be procured in the UK, and if so, where, and thirdly, proper application of such a material. I have done lots of research into the matter, but have been left fruitless. I'm sure someone can help.                                                                 Merry Christmas,                                                                                             icyseptember

Question by icyseptember   |  last reply


make a magnatic field and use only four 1.5 volt battreris

 i want to make a magnatic field only use only  four 1.5 volt battreris(4*1.5 volt).who can lift the 500 kg wait only for two sec, this megnatic field i can aply only 6 sqr inch plate only plz send me the digrame if u can.

Question by urosameer   |  last reply


I wonder...how could I create an strong electromagnetic field Answered

I want to create a strong electromagnetic field, strong enough to disturb my neighbours tv, he lets it on at full volume bugging me all night, any suggestions are appreciated and Thanks in advance

Question by SalemSnaKe   |  last reply


Can anyone give me some pointers on how to become better at Track sports??

By track sports, i mean events such as the 100m sprint, 400m relay, high jump, and long jump please help me! I'm a freshmen in highschool, and when i saw how some of the juniors and seniors ran, i can't help but feeling just a little discouraged. any help works! :)

Question by knexsniper1   |  last reply


A challenge of sorts: Field Kitchen

I want a military style field kitchen.  Not the giant 30,000 dollar trailers, the small but efficient kind towed by jeeps with 60 hp in the world wars. It has come to my attention that even these are quite expensive, not mention rare. I want to basically make a clone, except perhaps make it light enough to push by hand (should be possible by replacing non-essential heavy materials with light ones) and make it propane powered. Hopefully on a budget of a few hundred dollars. Any suggestions are welcome. A base/ pre-made trailer or cart to build it off of, material reccomendations, and most importantly how to implement the the cooking part. It needs tot be able to house 2 30 gallon pots and griddle top. pic is more or less what I'm aiming for

Topic by Bando_Red   |  last reply


Don't you just hate field trips? Comment on this topic if you do!

So, next week my class will be having a field trip to CHINA! FOR A WEEK! I mean, C'MON! I HAVE TO BE WITH MY CLASS, RESTRICTED TO WHAT I CAN DO, FOR 7 FRIGGIN DAYS! *Swears like crazy* LOL I spazzed out.... So, who here hates field trips?

Topic by Camisado   |  last reply


Debevec 360 degree light field display

I know some of you may have seen this already, but it's still pretty spiffy.You gotta love Debevec's projects. I do, anyway.

Topic by royalestel   |  last reply


Is there an airsoft field in northern Utah?

Is there an airsoft field in northern Utah. Specifically near Park City?

Question by piepieburger   |  last reply


Make a magnetic field detector ?

I dearly want to make a device to measure electromagnetic fields in the house ,since the presence of such has been more than obvious and at times annoying . My CRT monitors behave strange in my room . The geometry of one bends as i turn the monitor in one direction and at the same direction ,my spare one changes color to blueish like pale . Interestingly, they do it in the same direction no mater where i put them in the room . My turntable's (i am in to Hi-Fi gear ) cartridge reacts when i put it in some places in the room and i hear noise come out of the speakers until i reposition the turntable . Anyone have any ideas how i can locate the source ? Some simple device ,or schematic that will give me the ability to measure ,or at least detect to some degree the fields responsible ? Will be thankful for any answer .

Topic by soundsmyth   |  last reply


Strawberry Fields Forever - The Beatles

LET ME TAKE YOU DOWN CAUSE IM GOING TO STRAWBERRY FIELDS NOTHING IS REAL AND NOTHING TO GET HUNG ABOUT STRAWBERRY FIELDS FOREVER LIVING IS EASY WITH EYES CLOSED MISUNDERSTANDING ALL YOU SEE ITS GETTING HARD TO BE SOMEONE BUT IT ALL WORKS OUT IT DOESNT MATTER MUCH TO ME LET ME TAKE YOU DOWN CAUSE IM GOING TO STRAWBERRY FIELDS... NOTHING IS REAL AND NOTHING TO GET HUNG ABOUT STRAWBERRY FIELDS FOREVER NO ONE I THINK IS IN MY TREE I MEAN IT MUST BE HIGH OR LOW THAT IS YOU CANT YOU KNOW TUNE IN BUT ITS ALL RIGHT THAT IS I THINK ITS NOT TOO BAD LET ME TAKE YOU DOWN CAUSE IM GOING TO STRAWBERRY FIELDS NOTHING IS REAL AND NOTHING TO GET HUNG ABOUT STRAWBERRY FIELDS FOREVER ALWAYS, NO, SOMETIMES, THINK ITS ME BUT YOU KNOW I KNOW WHEN ITS A DREAM I THINK, ER,NO I MEAN, ER, YES BUT ITS ALL WRONG THAT IS I THINK I DISAGREE LET ME TAKE YOU DOWN CAUSE IM GOING TO STRAWBERRY FIELDS NOTHING IS REAL AND NOTHING TO GET HUNG ABOUT STRAWBERRY FIELDS FOREVER STRAWBERRY FIELDS FOREVER, STRAWBERRY FIELDS FOREVER...

Topic by FunkNattidelic   |  last reply


Long range magnetic field?

Hi,right now i am stuck with my research.I want to make a long range magnetic field 14 m (approx) please help me 

Question by ajose4 


Pool Table playing fied

Hi! I'm about to build a pool table (billiard table) and I wonder what material I should use for the ''field'' where you play. I wondered about plywood or something similiar. On all quality tutorials they want some stone or something (I don't really know) So what's the best and cheapest solution?

Topic by GroggDog   |  last reply


Golf GPS

New Golf GPS device for golf addict...its nice...visit are site...click here  

Topic by akira321   |  last reply


WWII era field phone: Answered

I'm looking for alternative uses for it. Right now I just imagine calling in an air strike when whataburger takes 20 minutes on a solitary chocolate milkshake. I've heard of people fishing with them but I'm a sporting man and that method doesn't seem very sporting. Unless of course we are in a WROL situation and I need to feed dozens quickly. Short of those two weak ideas, I'm stumped.

Question by tandem25   |  last reply


Adding a field to mention cost?

I think I have read many instructable pages and don't see that users mention the cost of the project. They do mention what materials and spares were used and where to procure them from, but I think that the uploading user should be requested to mention the  cost under the instructable, so that a new reader gets an idea of approximately how much money it is going to cost him apart from the time he has to put in. A new field at the end of the instructable whereby the users may enter cost of each item listed or the total cost of all the items in the project. This will greatly enhance the instructable pages. Thanks.

Topic by greatidea   |  last reply


Waveform of pulsed magnetic fields... Answered

I have recently been astoundingly interested in magnetic fields, for seemingly no reason. The point is, that in reading up on it, and being a big fan of the greatest mind of all time, Nikola Tesla, I have been stumped with a question that I can't quite seem to answer, and can barely wrap my head around. My question is this; when one takes a normal electromagnet and sends pulses through it, is the resulting pulsing field considered to be longitudinal or transverse waves, or something else all together? This has baffled me, and I am curious to see the answer. Another question I have is, what exactly does Tesla mean by "hertzian" waves, I'm assuming that that his "non-hertzian" waves are longitudinal waves, but I could be wrong. A little background on the question... This question arose when I was looking at the 'ible "spooky tesla spirit radio"  (something along those lines, I'm not sure the exact name). I read somewhere in the comments section that Tesla found Hertzian waves to be, for lack of a better term, a waste of time. This brought the question of different waves up, and one thing led to another and here we are!! Thanks for any and all answers!!

Question by arhodes18   |  last reply


Magnetic Field for hollow core?

I am working on a project in which I have to control a small setup at the end of a motor shaft using an electromagnet. The electromagnet needs to be around the shaft inbetween the setup and the motor. So I have used a metallic ferromagnetic spool(image attached) and wound 32 gauge wire on it to make it an electromagnet and put the shaft through it. Since this core made out of spool is hollow, I'm not sure how the magnetic field will behave. I tried powering up the one I made and it' seems to be both attracting and repelling a magnet's pole (edges attract while centre somewhat repels). Anyone got any idea about this?

Topic by Antzy Carmasaic   |  last reply


A Visit to Simon Field's Farm

Last Thursday my friends Quinn and Xander invited me along on a visit to Simon Field, a chemist, inventor, and entrepreneur. He lives on a small farm in the mountains south of San Jose, with his wife, a couple of alpacas, some goats, and a great many chickens, parakeets, and other parrot-like birds. And a tree house with a rope bridge going out to it, where he occasionally hosts parties. And a solar cell array from which they get most or all of their electricity. And a huge redwood tree, which someone in the '60's rented out to live in! And a hillside spring which under the right circumstances can shoot a fountain 30 feet into the air. And an art studio, and many artworks of various sorts just set here and there for one to stumble across. And a lot of salamanders... Check the image notes for details. Inside, his house is filled with science toys, spilling out from his workshop.  I had to make a separate forum topic on those to treat them properly!

Topic by rachel 


How to program gravity field? Answered

I am working on a program to learn about OOP (object oriented programing) and I want to make a program that lets you create planets and fling them around a sun. Here is the current code. Note, I am always actively changing it so the code may be broken at the time you click to open it. Sorry if that happens. https://www.khanacademy.org/computer-programming/solar-system-creator-oop/4441139047 =========================================== I know the gravity formula is F = (G*M1*M2) / R^2.  The problem is that F is a scalar, not a vector. I need to split this equation into X and Y components. But apparently, you cannot just simply define the X components and Y components separately using that formula because it is not a linear/inverse relationship. :( Anyone know what the easiest way to make gravity vector field?

Question by -max-   |  last reply


Simon Field's Science Toys

On my visit to Simon Field's farm, Simon showed my friends and me a great many awesome tricks and toys.  Of course, Simon does run Scitoys.com so this isn't surprising!  First we saw his workshop where he spends his time doing research, inventing things and writing books about them. He showed us a trick of floating aluminum pans off of a Tesla coil which I sadly did not get any pictures of. Next he got out a small vaccuum chamber and set some marshmallows in it. Yes they expand awesomely as the pressure declines, but what happens after that surprised me. Take a look: He also had a board which he had painted with homemade phosphorescent paint, made from ground-up strontium aluminate (I believe it was).  You could "draw" on it with a laser pointer: Here is an example of Franklin's bells, an electrical demonstration made famous by Benjamin Franklin.  A small metal clapper is suspended between two metal bells, each of which is hooked up to one end of an electrical circuit.  If sufficient voltage is passed through the circuit, the clapper is attracted to one bell, touches it, releases (or obtains) electrons to become similarly charged, whereupon it is repulsed.  It is then charged oppositely to the other bell and is attracted to it, until it touches that bell and swaps charges.  The cycle repeats as long as the circuit is maintained. The last thing we did was to eat whipped cream... that had been frozen in liquid nitrogen!  This turned Quinn into a dragon.

Topic by rachel 


running a camera and wireless station from batteries

Im thinking of setting up cameras away from my house and need advice on the power. basically they will be mounted on poles down fields from the house. what i plan on having is a network camera setup with the Ubiquiti wireless points (https://www.ubnt.com/airmax/nanostationm/). these will form a bridge of 2 or 3 cameras and the cameras will be connected to each, with one of the wireless points mounted on the top of the house to connect to.  what i cant figure out is the power. i would like to run a power cable down the field sometime but this will be costly and i want to try this out to make sure it works. i know deep cycle batteries would be best but i cant join the rest together. i know there will be a POE connecting into the wireless box and this will be split, so how would i join this to the battery, as would a converter be needed or any other suggestions would help. thanks!

Topic by ChrisD319   |  last reply


Airsoft field weapon for about $200?

Im a "n00b" , as some people would call it, to airsoft. Im looking for an aeg with 350+ fps, good accuracy and range. I prefer the m4 family of weapons, something that gives you that tactical look.

Question by zack attack   |  last reply


EMF [electromagnetic field] shield fabric?

Does anyone know how to make EMF [electromagnetic field] shield fabric?

Question by lindaoak   |  last reply


iPhone app typing fields not working

Hi. I just downloaded the Instructables app to my iPhone 4 running iOS 6.1. When I try to log in, I am unable to select the typing fields to enter my username and password. I tap and tap and tap, but nothing happens. I've tried restarting and reinstalling and got the same results. Any help? Thanks.

Topic by DELETED_tgee2   |  last reply


Can a Singularity Exhibit an Electrostatic Field ? Answered

What is wahh.......  a small black hole ...........  that's a singularity. If you bombard  it  with electrons ( which carry a negative charge ) will the tiny Black hole be attracted to your pet cat.   Cat fur looses electrons easily and acquires a positive charge.

Question by iceng   |  last reply


Track, Field, and Cross Country experiences

Hello everybody! This is knexsniper1 with a brand new forum for everyone to share their experiences! This time it's about athletics; cross country, track and field to be exact! In this forum, I would like everyone to share their experiences while competing, or just for fun; about the mentioned topics. you may share your fastest times in the 100 meter, farthest long jump, tallest high jump, but these are only some of the things that you can share. the choice is up to you! You can also use this forum for tips on competing, or you can share your ideas on how to compete better. Those of you who compete in these sports will have their name displayed here, and stats about them, such as their fastest times etc. Remember! I want this forum to be as "clean" and appropriate as possible, so don't be calling anyone a loser just because they can not run as fast as you, or jump as far as you, or anything! Just to start this forum off, I will be the first one to post my experiences on this! You may share anything you wish! some of my goals include competing national, and then moving on to international, beating the world record for high jump, and beating bolt at 100 meter! Have fun! knexsniper1: - 1 mile run: 5:27 - 100 meter: 10.62 Kiteman: -did an eight minute mile cross-country. That's a thirteen mile cross-country half marathon in less than an hour and three quarters. Smokedasphalt: -timings and distances: 100meters : 10.8s 200m : 22.1s Long jump : 7.08 meters. Triple jump : 13.76 meters. High jump : 1.80meters. Other achievements : Best athlete of the under-19 category of Pune city. Plus, loads of medals!! :D Now, I only concentrate on the 100m and long jump. Hope to participate in the internationals one day!

Topic by knexsniper1   |  last reply


Does the strength of the electromagnetic field of a coil depends upon the thickness of the wire? Answered

Whenever I have problems with the magnetic field strength of an electromagnet people tell to use a finer wire, I have some, its thickness is not more then the thickness of a hair, but whenever I use it, I have difficulty in connecting it with the battery because it's so thin it easily breaks off, and when I turn on the switch, it burns up instantly, maybe I am not using enough length of it. So does the field strength really increase with the decrease in thickness of the same length of the wire and same diameter of the coil, if it does than why?

Question by Wisaam   |  last reply


Is it possible to make the magnets lose it magnetic field permanently? Answered

I know magnets can lose its magnetic properties if exposed to heat, but is there a way to make the magnets permanently lose its magnetic fields?

Question by Plasmana   |  last reply


Can you charge a capacitor from the collapsing magnetic field of a coilgun? Answered

I was thinking about making a coilgun; not too powerful, only a small, compact (ish) version. Problem is, the capacitor takes a while to charge. What I was wondering is whether you return electricity from the collapsing magnetic field of the coil (after firing a shot) back to the capacitor, thus reducing charging time? And another thing; does a coilgun produce a weak EMP or something when it fires?

Question by .Unknown.   |  last reply


A little magnet experiment for everyone!

Some people just love to play with magnets and have a lot of them.If you are just like that and like to tinker a bit then I might have something for you.What magnets you use for the following experiment does not really matter but you should have 20 or 30 of identical properties.Can be disk magnets, block magnets or cubes, just not spheres ;)If you have a 3D printer you use it to make it fancy but a peice of wood, acrylic or such and a drill will do for round magnets.For cubes or flat packs you can make retaining walls on a flat surface.The experiment goes like this:I assume you already tried ways to combine your magnets to make them stronger, like stacking them up.But there is another way to really increase how strong they are combined.Start with one magnet at the center.Then like a ring add more magnets around it but with the oppisite side up.The created mounting solution is to prevent them flipping up and together, you want them as close as possible though.Add another ring and change the direction of the field again.Try this magnet, once all magnets are secured and compare the holding strenght to any other combo you tried so far.It will be much higher for the same amount of magnets.If you want to prevent the use of glue then try to create your mounting system with a really flat but strong enough bottom - this will then be the contact surface.Slightly reduced strength but you can re-use magnet with ease.But if you want to get a really strong one you need cube magnets.Like before you want to create some sort of grid, this time we go for a square.Start with cube in the center, facing north up.Leave enough space in your construction to add 8 more cubes around it - like on the face of a rubik's cube.Leave them empty for now !Add nother row, this time 16 to keep the square.Of course these one go with the south side facing up!Again one empty of 48 and then one last one with north side up with 196 magnets.Ok, to be fair, you wouldn't be able to pull it off a metal surface unless you used really tiny cubes, so if in doubt then go for just to 48 and leave the enter one out for now.Should be quite intense but similar to what any other shaped magnet would have done.Time to fill the voids!Add the cubes in the spce between the magnets so the north and south side face the magnets next to it!So basically sideways but in the correct orientation.You can then also add the center piece - try either orientation for that one ;)What happened now is that you forced the magnetic field lines to go up instead od for trying to go the easiest and shortest way to the next magnet.And "up" is where our magnetic surface would be, which provides the now overdue shortcut for the magnetic fields.Be amased how much stronger this version is and how much even 3x3x3 cubes would accomplish.With 10x10x10mm N52 magnets you might be able to use them support our wieght if you pull straight dwon from a horizontal surface...Ok, kidding, not just might, unless you are really big...One 10x10x10 might hold about 6kg.Stacked up a bit more but having 20 or stcked up would not be much stronger than 10.Even just 25 magnets with one in the center, one row of sideways orientated and one row with opposing field to the center one would be hard to remove from a steel surface.If we go with the imagined 6kg per magnet we could assume to get 25 x 6 = 150kg of holding power.Check you single magnet first then compare to the square of 25 ;)Consider using some plastic between magnet and surface so you can at least slide or pry it off if you have to.You can also combine magnets or a new one that has one side appear much stronger than the other.Meaning that for example on the north side it could hold 20kg while on the south side only 5.

Topic by Downunder35m 



where are airsoft fields near lyons,NY?

Where are airsoft/paintball fields in upstate NY

Question by aseaheru   |  last reply


Shallow depth of Field... From a tiny lens?

It is a nice effect to open up the aperture of a camera, focus on the subject, and allow the background to go blurry.  But many of today's still and video cameras have a tiny aperture. How can I get shallow depth of field from such a camera?

Topic by Toga_Dan   |  last reply


PEMF device that mimics earth's magnetic field?

I am very interested in making a pulsed electric magnetic field device that mimics the Earth's own magnetic field. It could be as simple as one single coil. That coil would have to have a magnetic field that measures in the 30 to 90 microTesla range, and it would have to be able to be pulsed in the 5 to 45 Hz frequency range, since that is roughly the strength and frequency of the Earth's own magnetic field Any ideas on how to make that happen? I am a reasonably intelligent person, but I am not necessarily technically gifted. So for somebody this might be uber simple, I don't know, but I am just not sure how to go about doing this. What do you think?

Topic by lapis lazuli   |  last reply


how far can an electromagnetic field reach?

For my project I need to know how far electromagnetic fields can reach. I am guessing its related to power and materials, but perhaps there is some kind of rough formula for calculating potential reach? By reach, I mean, how far can the magnetic field reach and attract (move) something, like metal fillings. Also, is there anyway to know how quickly a magnetic field can move something. In other words what speed will metal fillings move at when the electromagnet is switched on? Thanks all, Joel (the snow athlete)

Topic by snow athlete   |  last reply


fiber optic star field without attic?

Is there a way to make a fiber optic star ceiling without an attic??

Question by tim13211   |  last reply


Battle field 2:modern combat for ps2

Does anyone have a battlefield 2:modern combat for ps2 online account?If you do than leave a comment for everyone else to see. My account name is Alpha95 spellt exacaly like that. knex htr htr.OUTTTT

Topic by knex hater hater   |  last reply


6th Sense Device (To Sense Magnetic Fields)

I saw a program not too long ago (I believe it was from the UK) about an experiment that was done in which they outfitted a participant with a device that contained a magnetometer, as well as some number of vibrating motors mounted on a belt along his waist. It was designed so that overtime, his brain interpreted this incoming data as a "new sense" which allowed him to literally FEEL the magnetic directionality of the Earth. I'd really like to try this for myself, but am no good doing electronics projects from scratch. (I need guidance)  So is there anyone here who is up to the challenge of attempting this, or can anyone at least show me how it might be possible to create this myself.  I'd love to augment my senses full time and become a super human. haha Thanks in advance for any and all help. -Nick

Topic by foxymcfox   |  last reply


about programming emf (Electromagnetic Field) detector

Excuse me, I would like to inquire about emf detector. I saw one of the projects in makezine.com make emf with arduino, with LED bargraph. but here I replaced it with a small audio (8 Ohm), but why not come up with the perfect voice? This is my remake program   if(val >= 1){                    val = constrain(val, 1, senseLimit);     val = map(val, 1, senseLimit, 1, 1023);      total -= readings[index];                  readings[index] = val;           total += readings[index];                  index = (index + 1);                        if (index >= NUMREADINGS)                    index = 0;                               average = total / NUMREADINGS;              if (average > 50){                tone(10, 50, 100); delay(1000);     }     if (average > 150){              tone(10, 50, 200); delay(1000);    } if (average > 250){ tone(10,50,300); delay(1000);     } if (average > 350){ tone(10,50,400); delay(1000);     } if (average > 450){ tone(10,50,500); delay(1000);     } if (average > 550){ tone(10,50,600); delay(1000);     } if (average > 650){ tone(10,50,700); delay(1000);     } if (average > 750){ tone(100,50,800); delay(1000);     }         Serial.println(average);     delay(updateTime);   } } void tone(long duration, int freq) { duration *= 1000; int period = (1.0 / freq) * 1000000; long elapsed_time = 0; while (elapsed_time < duration) { digitalWrite(pinSpeaker,HIGH); delayMicroseconds(period / 2); digitalWrite(pinSpeaker, LOW); delayMicroseconds(period / 2); elapsed_time += (period);   } } please answer. Thank's.

Question by dzikriyana   |  last reply


Linear magnetmotor - the basics for a beginner

Designing what is said to be impossible can be tricky, so I will try to give you some tips to reach your goal a bit quicker.A lot of people these days try to start with a wheel.Makes sense in one way as the final goal obviously is something that would rotate.However, considering angles in a rotating system is far easier with a usable baseline!We developed the liear motor well after any rotating electric motor.But only because someone already invented it for us.Making it flat was then more or less about finding a need for it first, like the modern highspeed trains on a maglev principle.If you want to make something move then it makes no big difference if you do it in flat or round.Flat however leaves you more options and much easier adjustments.And you will need a lot of the later...IMHO the best size and option for linear is the N0 model railway system.Tracks are only 3CM wide and second hand carriages to salvage the wheels is cheap.Either way, how would you start?We have multiple choices, like single row of magnets or double, maybe even tripple.Same for the actual magnet orientation.Flat, angled, attracting or repulsing...They all work if you understand how they actually work.Not the principle, the magnets ;)You see, a magnet always has two poles and without trickery both poles will be of even strenght, size, angle to each other and so on.Playing on a small and flat track with little resistance allows to use tiny magnets, like 5mm disc ones.If you follow the common concept of two magnet rows either side at a slight angle then you are half way there.People spent a lot of time trying not only to let the cart being attracted by the first magnets but also to let them pass out at the other end.In case you wonder why:Being able to be "sucked" in means you will have some force pulling on your cart from the next stage.Being able to fully pass through and preferably gain speed, means the cart would go from one set of magnets to the next - motion is accomplished.Let me give you my personal favourites for 5mm disc magnets:1. The rows are at an angle of 4-5° like a slim V-shape.2. Same as above by with the orientation changed by 90°The first basically means you have the magnets facing up while in the second you would have them mounted vertically.Both have good and bad sides and I think it is easiest to start with the first option.Here you would have a row of magnets at a slight angle either side of the track.Lets say it is all pointing away from you, then the north row would be left, south row on the right of the track.If you start narrow or wide depends if you want attraction or repulsion forces to work with.Again, it makes no big difference really, just a different way of operation, most seem to prefer repulsion though thinking the forces are greater - this is not true though ;)A very often copied way of mounting the working magnet (s) on the cart is by placing a magnet with south facing down on the left and one with north facing down on the right of the cart.Here you have the big problem of manipulating fields.The forces are quite strong and it seems the obvious choice but should be left for the advanced classes.Let me try to explain:No matter the site of your work magnet it has a very narrow acting field.Means you have a lot of attraction forces going only downwards and not providing any energy to move your system ;)If you orientate a magnet (stack) so north faces to the right and south to the left on either side of the cart you have more options.If the stack or single magnet has the correct length to match the angle of the magnet rows then a funny thing happens.Assume the outer most magnet is at about the same distance from center as the first magnet in the row.Means the inner most and opposing one is further away and the attraction forces gain the upper hand.While moving along though it moves away from the magnet row and whie still gaining force the last magnet in the row stops the cart dead center.This is the common scenario you see on the web when people try and fail.Now if you change the length of your working magnet and position in relation to the magnets in the row you can use the changes to your advantage.You can add slim disc magnets either side of your stack and observe the change in behaviour and where the cart starts to be repelled or gets stuck.In a bad case it starts fast but then stops with a big wobble back and forth.The perfect balance and size means the cart is attracted once it comes close to the magnet rows.There should only be a tiny sopt of very little repulsion right before the cart takes off.Like a hair trigger on a good gun if you know what I mean.It should then see some accelleration till about magnet 5-7 in a row of 14.From there it should level out and roll trough and keep rolling.I assume your first attempts now get you to the point where you cart start really nice, slows down a bit and seems just to miss a tiny extra push to make it out.It it shoots to the last magnet in the rows and then settles back to one or two before the end you are close!We have now two basic ways of manipulating the magnetic fields in our favour, or to "cheat" phsyics.Closing the gap.You will have realised by now that you need at least two stages for your system to be tested properly.Preferably 3 to get a 120° angle in a rotary conversion, but 5 would make sure there is hickups.This also means distance is now something to play with.Remember the pull before get at the same level with the first magnet in the rows?This is the first force we utilise by bringing the second stage at a distance CLOSE to take over the pull.Close because we don't want it to pull the cart out just like that.It would create a big "bump" and in a rotary system massive and unwanted vibrations.Instead we weaken the last magnet in either row.We still want to keep its pull but not so much the holding force that makes our cart go stuck here.Placing a magnet orientated in the same direction as your rows at the end of the row will change how and where the field of the last magnet in the row goes ;)Just to be precise: If the magnet in the row is north up and south down then the added magnet should have the poles 90° to that and in the same direction as the row.Depending how high, how close and with wich pole you place it the fields will change.You want to lower the locking force by at least 50% here - that will be suffient to overcome the holding force and gives the next stage a good chance to take over.It can also help to provide a sacrificial pole below the last magnet in the row.Again if north would be facing up then the lower magnet would also face north up but with a small distance to the upper manget.Ok, what happens here exactly?If I would want to be precise here you would need to read an awful lot, so make it simple...The lower magnet provides a way for the upper magnets south pole to get somewhere else instead of back to its original north pole.It also means there is another north pole "pushing" the north of the upper magnet more flat at the bottom half.This weakens the field strenght.Distance is key.The added magnet at the end does a similar thing.It provides attraction or repulsion forces that affect the field shape of the last magnet in the row.Imagine you have north facing towards the last magnet:You would push the last bit of the field up while also providing a very sharp end instead of a big round shape.The south pole of the last magnet also gets attracted by this added magnet, even more with one magnet below it.With those two added magnets you should be able to fully overcome the binding effect stopping your cart.It won't start and keep going when you let go of it half way down the track though, you need to start with the first magnet or give it a push to overcome the first binding effect.After that momentum takes over.If it really is that simple then where are all the successful videos about it?They are out there, you just need to look quite long for them.Most people still literally think only linear.A magnet has north and south and we can't change it - but we can...With field manipulations as above and shielding we get so much more than what physics currently dictates.Keep in mind that adding shielding under your rows of magnets will also affect how all works together ;)Some people forget this when using ferromagnetic things way too close to their testing area.Distance is also vital to keep in mind when experimenting.The closer two magnets are greater their forces to each other.You can utilise this for example by lowering magnets that seem to be far too strong in your configuration and cause a binding effect ;)And as said, shielding is nice thing for triack too - imagine what would happen with sielding on the sides of your magnet rows... ;)Make a negative into a positive!Extremly strong binding forces at a certain point in your track design can mean you might be able to utilise it instead of trying to waste it.Added magnets can divert the field to quite some extend.Shielding however can also direct them somewhere else - like in the core of a transformer where it all goes in a great circle.Even strips of shielding connecting magnets from one row to the one on the other side of the track can be utilised.Like that you turn two small magnets into one long one with twisted poles at the end.Provides more field strenght too and makes it good for areas with little to no attracting force to the cart.Then there is bigger design...Some people add a center magnet.With one on the cart and one in the center of the track you can create a cancellation field.The rows bind while the center magnet wants to push.If place where there is still enough forward momentum or even acceleration but close enough to the binding magnets it is possible to greatly lower the binding effect.But keep in mind you need to consider the added repulsion or compensated the field so it is most active towards the moving direction and less strong to where the cart is coming from.Advanced manipulations.You can machine magnets, sandpaper, file, grinder, CNC....Imagine you cut a square dice magnet from one corner to the other.Depending on how you have the field orientation you can end up several variations.But if north faced up in your dice then it will still face up in the cut pieces!Cut a pyramid and you end with a big flat south pole and a pointy north pole - and with extreme field strenth in this pointy bit.Similar story with half moon shapes.Imagine you machine a flat block magnet so you have a half moon with its pointy bits facing down and big round bit up.If north was up in the block and you shape the moon correctly then you end with two strong south pole points and a north pole that is strongest right between those points.Why is this so interesting you might wonder?Imagine you already know a magnets pole does not care if gos back to its own opposite or that of a different magnet.Then you also know you can machine and shape magnets to your will.Now imagine that for a change:Precisely machined pyramids that have the top chopped off.All tops in this example facing being the north poles and big bottom south.If you then machine a precise iron core block you make a nice cube.With magnets we need really good glue and a good press to make it happen.But if the center core is of proper size then we end with a block magnet that has a south pole on all sides.Of course to be 100% perfect we would need a zero tolerance gap but good glue and high forces can come quite close.Works as a sphere too but would even have clue where to start to machine the magnets LOL

Topic by Downunder35m 


how do you know the size of the magnetic field with respect to the amount of electricity?

For example you have an electromagnet and it has an electromagnetic field how can you know how much electricity to put to make a magnetic field with a specific size (like this many volts equals this many meters in diameter)

Question by HassanA32   |  last reply


Very old shielding materials and techniques for permanent magnets and resulting possibilities

Forromagnetic meterials are not just called that for no reason.It comes from ferrous - iron.Iron has the highest permeability at normal temperatures.That means a magnet is attracted to it very strongly.We utilise this for transformer cores, the stuff inside a relay and the moving latch of the relay itself.Like current from an electrical system magnetic fields like to take the easiest route possible.Air is a very bad medium, so any iron close by will be prefered even if it is at a slight distance.You can check with a magnet, a steel bar and some iron shavings - please cover the are with plate first ;)Slightly less known is the option to also guide and extend the magnetic field this way.If you check how far the magnetic field of a magnet reaches and note that distance,then you can add some steel bars or rods at the poles - the field will extend through the metal.The most powerful example of this are the shielded magnets used for hooks or speakers.Except for a tiny area the entire magnetic flux goes through the metal.So in this lefover area the magnetic flux density will my many times greater than what the magnet alone would be able to.What most people don't know is that magnets also interact with other magnets in terms of their fields changing and distorting.The Halbach Array is a good example of this.Seen as a single magnet the array would have one weak and one strong side instead of even strenght for both.Wherever magnetic fields change a conductor can produce electricity or current.This in return causes an electromagnetic field that opposes the one from the magnets.Just drop a magnet through a copper or aluminium pipe ;)Since these distortions are widely unknow to the hobby tinkerer mistakes can happen ;)In the early days of exploring science some people already knew about shielding.And they also knew that certain metals have certain properties.Where it is quite hard to create a good coil from steel wire, copper works fine as it is not magnetic.What would then a copper shielding do?If you have two moving magnets with only a tiny gap then the resulting field distortions are quite huge.A copper shield around the magnet like a pipe would then react to these changes and also create a megnetic field that works in relation to the enclosed magnet.In simple terms it means the shield would let the magnet appear weaker or stronger depending on the field change.A quite old document I found gave some hints on how people thought in different directions back then.It was in regards to the design of a magnet motor by the way.Here various magnets were shielded in tube made of a copper-bismuth-alumium alloy.These tubes were then electrically connected so it created a single loop conductor.The claim was that the resulting electromagnetic field of this ring would drive the fields of the enclosed magnets sideways out of alignment.Like bending straight pastic tubes sideways.This "pulsating" would always happen when the magnetic binding forces reach max and so basically drastically weaken this binding effect.Another document talks about a "magnetised brass rod".A holes of the rod diameter is drilled through a block magnet.Not from north to south but through the middle where the flux is greatest.The claim here was that if that rod rotates fast enough a very low voltage with a very high current will be generated.Sounds easy and interesting enough that I might have to test one myself one day.The best one however is what I consider a hoax or being as good as Starlite.Someone back in 1908 claimed to have created a material the reflects magnetic fields.In lame man's terms it would be like an insulator around some electrical wire.The claim and some pics showed it, was that no magnetic field can pass the material.Or to be correct only a tiny fraction of what would be possible through air.A small magnet inside a longer tube of this material would create almost the same attraction to steel at the tubes ends as on the magnet itself.Measurements showed the field strength would be almost equal to a long mangnet of the same field strength.Imagine guiding the field of a big and powerful magnet through a tube around some corners or other magnets and then end in just a tiny hole for the entire flux...Too bad he never shared his secret formula to anyone knows to mankind.Isolation...Imagine you have an array of changing magnetic fields and quite strong magnets.Then you might face the problem that your focus on the "working" end neglected the other end of the magnet (stack).Providing some iron core material will keep thes field lines contained and away from interfering with your setup ;)But it also allows to use te otherwise unused end of your magnets more directly.For example by guiding to another magnet to affect its field strenght ;)Placing a sheet or steel between two magnets in a setup provides a "shared pole" so to say.If you have a north and south pole on a rotor at a distance of 5mm then a sheet of steel between will drastically weaken the strenght and reach of this combined field.It is like pulling the arch between the magnets down to make it more flat.And at and an angle the resulting field will also be slightly angled ;)Capping...When I first encounter this many years ago I couldn't really make sense of it.Quite complex..If you check the magnetic field lines with iron filings or similar then you notice how they go in a rounded manner from pole to pole.This is because the single field lines are of equal polarity and will dirve apart like opposing magnets.By capping the ends of a magnet you provide a short.Instead of diverting out like mad they will follow the cap and create very intersting magnetic field in return.If both poles are capped it is like pressing the magnet flat but without having a field on top of the oles - only aorund the center part.For this the thickness much must match what is required for the flux density.As a rule of thumb: if the end is still very magnetic then it is not enough material tickness ;)Interacting fields in a tube...This one is quite old too and seemed to have found no usable inventions apart from simple magnetic spring replacement systems.But it gave me some clues about Tesla "earthquake machine" ;)If you place a magnet in a tube and at it's ends magnets with opposing fields to the one inside then you can fix this magnet in place.Push one magnet deeper and the distance from the inner magnet to the other end will shrink the same amount.In this old paper two coils were around the pipe with the inner magnet between them.In this gap and at about the same width as the magnets length another coil was placed.Violent shaking would then create electrical energy at much higher level then modern shaker torches.In return an AC current on the outer coils would cause the inner magnet to move back and forth to create electricity in the center coil.According to the paper possible uses include: core less transformer, measuring minute changes in AC voltages, providing free power from a running motor...The last one had me stumbled for a very long time.Until I considered a different configuration.The whole thing is basically a linear DC motor - with correct timing of course.And in some motors we use permanent magnets.I am starting to wonder what would happen if we would design a rotor magnet like this?The running motor would be subject to constant field changes that affect the rotor.And a normal motor is always "even".By using four magnets instead of one we can push the field really flat.This means the area where the coil would operate (about 1/5 of the magnets area) will have a much stronger field.The resulting torque should be higher by about 25% !!Even a simple two coil model setup should show a significant increase in performance here.Timing is critical here but I tried some calculations based on 8 poles and the required "on times" for the coils.In a standard motor configuration with a single rotor magnet the coil is active for about 12° of the rotation.With a 4 magnet configuration this "on time" can be reduced to under 8° of the rotation to get the same amount of torque.An energy reduction of about 4% if you neglect losses and only think in time.If you think in terms like impulse energy then we are talking of about 15% !Shorter on time but still much higher flux density overall than for the long standard timings.Going the long run now:If you check how most DC motors work then you realise soon that for most one rule seems to followed.Only use one coild pair at a time.This is quite contradictive if you consider the geometry and options.A dual commutator would allow to use a second coil pair with a field OPPOSING the magnets instead of being attracted to it.After all: on you bike you pedal with both legs and not just one...And if you do it professionally then yu do the same as I suggested for the motor - you use the up pull of your legs as well.Doing it brushless only requires amodified h-bridge desing to drive the second coil pair at the right timing.Some will now say that it requires twice the energy, I say that for the same motor size your get twice the torque!Just imagine what that means in possible weight reduction for a motor - or its size to deliver the same torque at the same power levels when a normal motor is used ;)The more poles the more complicate the precise timing but no big deal really with modern electronics.Can it be improved even further?I though long and hard about that one until I considered EMF.A DC motor produces a lot of it when the elecromagnetic field collapses in the the coils.We do not utilise this energy...There is a tiny delay until the released energy levels are at max.My theory is that it should be possible to divert this energy into another coil set.If that coil is not the next active but still within a strong enough field area then the EMF would actually add to the drive of the motor.Only downside is that according to my calculations at least 16 poles would be required to get an optimum result.Way above of what I can create in my little garage :(In theory it should then be possible to reach about 98% efficiency for the motor....

Topic by Downunder35m   |  last reply


Would You Guys Like a "Wireless Power Kit"?

Hello, This was moved to the forums from https://www.instructables.com/answers/Would-You-Guys-Like-a-Wireless-Power-Kit/ I am the author of the Wireless Power instructable here. [1] Over the course of the past year or so, my instructable has had just under 200,000 views and 600 comments. I have found that many people are actually 'recreating' my circuits and making their own wireless power systems. I was thinking the other day, wouldn't it be great if there was a "Wireless Power How-to Kit," which would include a how-to guide, a solderable circuit, and all the components necessary to make a wireless power system. This would be for all of the people who would like to explore inductive coupling, but do not know where to start. I think this kit would help a lot of people... What do you think? Would you like a kit like this? Any tips for creating the kit? [1] https://www.instructables.com/id/Wireless-Power-Transmission-Over-Short-Distances-U/

Topic by robotkid249   |  last reply


How do I capture the collapsing field of a coil so I can use it again?

If I energize a coil and then switch it off, I get a collapsing field, I would like to capture this field and use it to energize a seperate coil, is that possible, and how would I do it. Thanks.

Question by joecarey   |  last reply