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Thread: Winding a solenoid several layers in depth

  1. #1 Winding a solenoid several layers in depth 
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    I'm building a large electromagnet and have a question about winding the solenoid that will fit around the core. A solenoid consisting of only one layer of wire is simple, you just wind the wire around the core from, let's say, left to right as tight as you can. How is that you build up layers though. Do you put one layer down from left to right and then go back again from right to left? This to me seems incorrect but I can't think of another way of doing it. Could somebody help me out? I'd appreciate any and all help.

    Thanks,


    Aaron


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    Don't take my word for it but I think that's how it's done. One question though, why does it seem incorrect?


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    I have no expertise on electromagnets but to me it seems that I would want the electrons moving in the same direction. To me it would seem that if the are flowing in the copper around the core going lets say clockwise right to left and then, still going clockwise but now left to right then I would assume that would cause conflict in the field that was created. But if going back and forth in the winding is correct than I would assume that what creates the field is the either clockwise winding itself and not direction of the winding down the solenoid.

    God, it's so hard to talk about things that you really don't have the vocabulary to articulate. I hope I made sense in that last paragraph.
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    I do know that the clockwise (or counter-clockwise) bit is the important part.

    Think about how far an electron goes left or right during one turn (not very), and it's moving electrons that create a magnetic field.

    Again, I may not be the best person to ask, but I think that going left or right or both would only have a tiny effect on the magnetic field.
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    I think the OP meant left and right as viewed from the side, like the way thread is wound on a spool. That would seem to be the logical way to do it. It wouldn't affect the magnetic field. Winding it clockwise then counterclockwise wouldn't work. The clockwise windings would cancel the magnetic field of the counterclockwise.
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    Thanks to the both of you for your help. I'll give it a try and see how it goes. I have a teslameter coming the mail tomorrow so I'll know if it works or not. Again thanks, I think I'm going to like this forum though right now I only have questions to contribute.
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    Quote Originally Posted by chekhonte
    I have no expertise on electromagnets but to me it seems that I would want the electrons moving in the same direction. To me it would seem that if the are flowing in the copper around the core going lets say clockwise right to left and then, still going clockwise but now left to right then I would assume that would cause conflict in the field that was created. But if going back and forth in the winding is correct than I would assume that what creates the field is the either clockwise winding itself and not direction of the winding down the solenoid.

    God, it's so hard to talk about things that you really don't have the vocabulary to articulate. I hope I made sense in that last paragraph.
    I'm not sure that I follow "left to right" or "right to left", but unless you want the fields from the current layers to cancel one another, you need to keep the wire going in the same direction -- clockwise or counter-clockwise as viewed from one fixed end.
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    What I was trying to describe was this: As you wind the wire up the core you might be going from left to right, then when you reach the end of the core you are still winding in the same clockwise direction but you start winding from right to left until you get to the other end of the core. Sorry, I find it hard be articulate when trying to write about two different motions in single object. I'm sure that my question has been answered.

    Thanks!
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    Quote Originally Posted by chekhonte
    What I was trying to describe was this: As you wind the wire up the core you might be going from left to right, then when you reach the end of the core you are still winding in the same clockwise direction but you start winding from right to left until you get to the other end of the core. Sorry, I find it hard be articulate when trying to write about two different motions in single object. I'm sure that my question has been answered.

    Thanks!
    I believe your best DC magnet will be created with a single wind in all the one direction.

    However in AC you can create two separate circuits, wound or fed in opposite directions and it will still create a magnet.

    Some multi leg transformers will operate even though you connect, the two primary coils out of order or opposed to one another. I do not recommend it, I follow the wiring diagram. I just noted that it functioned, under a partial load.

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    William McCormick
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    Dang, I am using a DC power supply. You mentioned a wiring diagram, where can I find such a thing?
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    Quote Originally Posted by chekhonte
    Dang, I am using a DC power supply. You mentioned a wiring diagram, where can I find such a thing?

    This might be interesting to you.











    I believe this is a magneforming coil, to create that rib effect in the keg.



    All the solenoids and relays I have seen and or taken apart are wound like a fishing line on a reel. Or as someone said thread on a spool.


    If you look at that picture with the horse shoe magnet. You might be able to wind a straight rod, like that and get a similar effect. But I have not tried that. I will put that on my things to do list.


    Sincerely,


    William McCormick
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    Quote Originally Posted by William McCormick
    Quote Originally Posted by chekhonte
    Dang, I am using a DC power supply. You mentioned a wiring diagram, where can I find such a thing?

    This might be interesting to you.











    I believe this is a magneforming coil, to create that rib effect in the keg.



    All the solenoids and relays I have seen and or taken apart are wound like a fishing line on a reel. Or as someone said thread on a spool.


    If you look at that picture with the horse shoe magnet. You might be able to wind a straight rod, like that and get a similar effect. But I have not tried that. I will put that on my things to do list.


    Sincerely,


    William McCormick
    You do realize, don't you, that there is no wiring diagram for any circuit, let alone a power supply on those pages ? Do you know what a wiring diagram is ? A power supply ? Did you bother to read the question ?
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by William McCormick
    Quote Originally Posted by chekhonte
    Dang, I am using a DC power supply. You mentioned a wiring diagram, where can I find such a thing?

    This might be interesting to you.











    I believe this is a magneforming coil, to create that rib effect in the keg.



    All the solenoids and relays I have seen and or taken apart are wound like a fishing line on a reel. Or as someone said thread on a spool.


    If you look at that picture with the horse shoe magnet. You might be able to wind a straight rod, like that and get a similar effect. But I have not tried that. I will put that on my things to do list.


    Sincerely,


    William McCormick
    You do realize, don't you, that there is no wiring diagram for any circuit, let alone a power supply on those pages ? Do you know what a wiring diagram is ? A power supply ? Did you bother to read the question ?
    It shows the basic methods of creating an electromagnet. I thought it might be interesting.

    I believe I have some great diagrams for power supplies. What kind would he like to build? I could not figure out who he was replying to.


    These diagrams I posted do show the basic principles.



    Sincerely,


    William McCormick
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    Wow, thanks for the scanned text and diagrams.

    I don't trust myself with building a power supply. I'm currently trying to use a 30 volt 50 amp power supply. I hope that it's enough.

    Last night I tried both a single wind and multiple wind solenoid. With the single wind I was only able to generate around 150 gauss. With the multiple wind (around 4 times up and back) I was able to generate 400. I was using cheap round wire for both of them and the winding job on the second attempt go a little sloppy. I have 20 lb of square wire coming and I'll try it again with a more careful wind. I'm hoping to break 2000 gauss on the surface of the iron.
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    Quote Originally Posted by chekhonte
    Wow, thanks for the scanned text and diagrams.

    I don't trust myself with building a power supply. I'm currently trying to use a 30 volt 50 amp power supply. I hope that it's enough.

    Last night I tried both a single wind and multiple wind solenoid. With the single wind I was only able to generate around 150 gauss. With the multiple wind (around 4 times up and back) I was able to generate 400. I was using cheap round wire for both of them and the winding job on the second attempt go a little sloppy. I have 20 lb of square wire coming and I'll try it again with a more careful wind. I'm hoping to break 2000 gauss on the surface of the iron.
    That is a big power supply. DC ? Do you have some means of limiting the current ? 50 amps is rather a lot to carry for any length of time. What gauge is the wire ?
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    Yes, it's a dc power supply but I forgot to mention that it's variable and not 50 amps continuous. I actually don't expect to use all 50 amps, in fact I would be worried to have it up to 25 amperes for over a couple of minutes. I have a infrared thermometer but it's hard to tell what the temp would be deep inside the coil.

    I ordered 10 gauge wire and 19 gauge. Both have a thermal rating of 200C.
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    Quote Originally Posted by chekhonte
    Yes, it's a dc power supply but I forgot to mention that it's variable and not 50 amps continuous. I actually don't expect to use all 50 amps, in fact I would be worried to have it up to 25 amperes for over a couple of minutes. I have a infrared thermometer but it's hard to tell what the temp would be deep inside the coil.

    I ordered 10 gauge wire and 19 gauge. Both have a thermal rating of 200C.
    That is important. You are being prudent. The 10 gauge ought to be Ok for most of what you are doing but be careful about overloading the 19 gauge wire. Here is a table with current limits for various wire sizes. You probably would be OK at slightly higher levels for a short period of time, but if things feel hot, shut down the current. And be careful about any flammables, particularly vapor, that might be nearby.

    The temperature deep in the coil wil pretty close to the temperature on the surface, for a rather short period of time. The inside of the coil will also loose some heat to whatever you are usisng for the core, until that too heats up. Once a little time has passed and heat transfer becomes important the outside will be cooler, quite a bit cooler since it will see air cooling and can radiate.

    http://www.powerstream.com/Wire_Size.htm This link will give you current ratings for various wire sizes. It also seems to have a calculator that would determine voltage drop for given wire lengths, which would let you calculate the power being disipated.

    Be real careful with anything that William McCormick tells you. He doesn't know what he is talking about. He doesn't know that he doesn't know. You could get hurt.
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  19. #18 Re: Winding a solenoid several layers in depth 
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    Quote Originally Posted by chekhonte
    I'm building a large electromagnet and have a question about winding the solenoid that will fit around the core. A solenoid consisting of only one layer of wire is simple, you just wind the wire around the core from, let's say, left to right as tight as you can. How is that you build up layers though. Do you put one layer down from left to right and then go back again from right to left? This to me seems incorrect but I can't think of another way of doing it. Could somebody help me out? I'd appreciate any and all help.

    Thanks,


    Aaron
    Yeah that would cancel out. I would just increase the amount of turns in the wire if I wanted to get a stronger field. I believe that the only two things that determine the magnitude of the field are the number turns in the solenoid and the current. So if you put enough turns in there you should still be able to get the size field your looking for without having to worry about the danger of large currents.

    Oh 25 amperes sounds a little scary to me too, heh.
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    I think the left-to-right bit is a bit confusing. I'm pretty sure as long as you always go clockwise (or counter-clockwise), going back and forth from one end to the other won't matter. Overall, the number of turns should matter most.
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    The kind of wire usually used to make an electromagnet is called "magnet wire." You can buy it on the internet or Radio Shack. This has very thin insulation allowing you to put more turns into a smaller space. More tunrs means you can get higher magnetic field per amp.
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by chekhonte
    Yes, it's a dc power supply but I forgot to mention that it's variable and not 50 amps continuous. I actually don't expect to use all 50 amps, in fact I would be worried to have it up to 25 amperes for over a couple of minutes. I have a infrared thermometer but it's hard to tell what the temp would be deep inside the coil.

    I ordered 10 gauge wire and 19 gauge. Both have a thermal rating of 200C.
    That is important. You are being prudent. The 10 gauge ought to be Ok for most of what you are doing but be careful about overloading the 19 gauge wire. Here is a table with current limits for various wire sizes. You probably would be OK at slightly higher levels for a short period of time, but if things feel hot, shut down the current. And be careful about any flammables, particularly vapor, that might be nearby.

    The temperature deep in the coil wil pretty close to the temperature on the surface, for a rather short period of time. The inside of the coil will also loose some heat to whatever you are usisng for the core, until that too heats up. Once a little time has passed and heat transfer becomes important the outside will be cooler, quite a bit cooler since it will see air cooling and can radiate.

    http://www.powerstream.com/Wire_Size.htm This link will give you current ratings for various wire sizes. It also seems to have a calculator that would determine voltage drop for given wire lengths, which would let you calculate the power being disipated.

    Be real careful with anything that William McCormick tells you. He doesn't know what he is talking about. He doesn't know that he doesn't know. You could get hurt.
    That table really helps. I might order some thicker gauge wire and try to push the amps a little bit. I have some rather massive iron rods that I want to try out. 12 inches by 2 1/2 inches cylindrical.
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    Quote Originally Posted by chekhonte
    That table really helps. I might order some thicker gauge wire and try to push the amps a little bit. I have some rather massive iron rods that I want to try out. 12 inches by 2 1/2 inches cylindrical.
    Be careful how you use those ampacity tables. Those are designed for cable in free air. Your cable is wrapped around on itself, and would have to be derated quite a bit unless you are just energizing it intermittently.

    Before you go down that road of increasing your wire gauge, make a few simple calculations. The magnetic flux will be proportional to the current multiplied by the number of turns. From the diameter of the wires, including the insulation, figure out how many turns will fit on your core with each size wire. Then use the current rating of the wire, and see how many ampere-turns you will get for each wire size with the maximum current in the wire.
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    Quote Originally Posted by chekhonte
    Wow, thanks for the scanned text and diagrams.

    I don't trust myself with building a power supply. I'm currently trying to use a 30 volt 50 amp power supply. I hope that it's enough.

    Last night I tried both a single wind and multiple wind solenoid. With the single wind I was only able to generate around 150 gauss. With the multiple wind (around 4 times up and back) I was able to generate 400. I was using cheap round wire for both of them and the winding job on the second attempt go a little sloppy. I have 20 lb of square wire coming and I'll try it again with a more careful wind. I'm hoping to break 2000 gauss on the surface of the iron.
    It is funny, because they have been winding magnets for hundreds of years. Yet our ability to communicate about them is poor. I am actually reprimanding myself.

    When I was saying a single wind, I just meant in all one direction. However after rereading it I can see how that could mean just one layer. Ha-ha. Sorry about that.

    Most of my electromagnets are multiple layer magnets. They do seem to work well.

    These are two magnets I made. The first one is just a simple single core magnet, that you can see repulses aluminum. When turned on.

    The second one is a double core magnet, and you can see that it will even allow aluminum to be pushed to it.

    http://www.Rockwelder.com/WMV/Magnetism/Magnetism.html

    http://www.Rockwelder.com/WMV/AlumEl...tromagent.html

    I tried to find the Web site for a reprint of a book I have about double core magnets. The book has information about magnets created back before 1935. But the web address no longer exists. If I cannot find a link to them I will post a scanned in copy of the magnet.

    If you can use a power supply safely you can build one.





    This is a bit off the subject, but it is a sterling engine. Pretty cool. I came across it while searching for the magnet book.
    There is a video on that page that shows how it works.

    http://cgi.ebay.com/Buy-a-Low-Temper...QQcmdZViewItem

    Sincerely,


    William McCormick
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    Quote Originally Posted by DrRocket
    Quote Originally Posted by chekhonte
    Yes, it's a dc power supply but I forgot to mention that it's variable and not 50 amps continuous. I actually don't expect to use all 50 amps, in fact I would be worried to have it up to 25 amperes for over a couple of minutes. I have a infrared thermometer but it's hard to tell what the temp would be deep inside the coil.

    I ordered 10 gauge wire and 19 gauge. Both have a thermal rating of 200C.
    That is important. You are being prudent. The 10 gauge ought to be Ok for most of what you are doing but be careful about overloading the 19 gauge wire. Here is a table with current limits for various wire sizes. You probably would be OK at slightly higher levels for a short period of time, but if things feel hot, shut down the current. And be careful about any flammables, particularly vapor, that might be nearby.

    The temperature deep in the coil wil pretty close to the temperature on the surface, for a rather short period of time. The inside of the coil will also loose some heat to whatever you are usisng for the core, until that too heats up. Once a little time has passed and heat transfer becomes important the outside will be cooler, quite a bit cooler since it will see air cooling and can radiate.

    http://www.powerstream.com/Wire_Size.htm This link will give you current ratings for various wire sizes. It also seems to have a calculator that would determine voltage drop for given wire lengths, which would let you calculate the power being disipated.

    Be real careful with anything that William McCormick tells you. He doesn't know what he is talking about. He doesn't know that he doesn't know. You could get hurt.

    On the contrary, I know that no one is all that great of a magnet scientist. Even the best that I know. Because they still fumble with the direction of electrons and what they do.

    You do have to be very careful with magnetic fields. Because if you are in the magnetic field, and a disruption or ARC occurs. You could get some nasty rays.

    I get current to run through me all the time holding onto those magnets. The magnetic field allows electricity to flow right through the insulation of the wires feeding it.

    I have had ceramic magnets near regular 110 volt lines, cause electricity to breach the insulation of the standard 110 volt chord.

    So although I may not be a professional magnet expert, I do have about 44 years of experience with them. And with working with the best in their fields.

    I can also tell you that I am forever reprimanded on these boards for giving out safety tips about power. I am often accused of being to safety conscious or accused of scaring away new guys interested in the field.

    No one mentioned that a DC power supply is at any moment an AC power supply, if you get an intermittent break, and or ARC.

    I have been in magnetic fields, that caused my face to get involuntary tics, while there was energy put into the field. The energy from a breaking rubber band. I had a couple miles of #39 magnet winding wire, and I was putting some of it on smaller spools of wire. When my drive rubber band broke it caused my face to get muscle spasms. I did it a couple times and it happened every time.

    I have seen light inside my head from a start capacitor, that exploded in a five horse power electric compressor motor. And I was twenty feet from it. I could feel the magnetic field engulf me.

    I have been welding for almost 37 years now. I have been repairing welders for about 30 years. I know not to weld on induction devices, ever. But if you want to spread rumors and lies, I probably cannot stop you.

    You are actually supposed to shield magnetic coils with multiple walls of grounded steel. So no one is that good or cares that much.

    In this movie below you can see what a magnetic coil is capable of. It can raise voltages to very high voltages. So although you are only dealing with a nine or thirty volt power supply, you could still see lethal voltage as soon as a transformer/magnetic coil is introduced to the circuit.

    http://www.Rockwelder.com/WMV/sparkyhq.wmv

    I have had my hands on both leads of a transformer, as it was disconnected, from a low voltage test circuit. Wow it wakes you up.

    I get zapped from my laser power supplies all the time. Because I often film them in the dark. Or I am putting them away, and forget they do not discharge. I have some experience.



    Sincerely,


    William McCormick
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    Thanks all of you for your concern for my safety. I hope not to get hurt or worse too from electrocution. I keep track of the temperature with my IR thermometer and don't let the temperature exceed two thirds of the wire rating before I start to slowly power down the magnet. I understand that it can be dangerous to a power supply to quickly power down the magnet and collapse the magnetic field.

    The reason I'm building this electromagnet is to build a magnetic sculpture using ferrofluid much like sachiko kodama's advanced work. Here's a video for those not in the know.


    http://www.youtube.com/watch?v=me5Zzm2TXh4



    At the risk of sounding obsequious I'd like to thank you all again. I understand that this subject is confusing to write about accurately--Believe me, nobody is more confused than I am, but I am starting to understand the basics. My first two magnets were failures but I'm going to continue to try and persevere while also trying to not kill myself or my girlfriend.
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    I do have a lot of years, doing this kind of stuff. I have been designing circuits and electrical equipment for many years. For single and three phase equipment. I work on high voltage equipment all the time. I design energy management control systems for them.

    From large Mammoth roof tops to small multiple systems for department stores.



    But I do have fun too.


    http://www.rockwelder.com/funny/MPGfun.wmv


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    William McCormick
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    Quote Originally Posted by MagiMaster
    I think the left-to-right bit is a bit confusing. I'm pretty sure as long as you always go clockwise (or counter-clockwise), going back and forth from one end to the other won't matter. Overall, the number of turns should matter most.
    Your right as long as you go the same direction the field won't cancel. It's given by the right had rule point your thumb in the direction of the Current and your fingers should be pointing in the direction of the field at that point. What I think we were all saying is that if you wind it one way around the tube, and then want to add another layer, you may end up canceling the fields out depending on which way you wrap back around. But your correct the only thing that matters is that the current's stay in the same direction.

    I also need to correct my post, it's turn's per meter or per unit length that really matter. So basically then density of the turns, like what Harold had said.
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    Quote Originally Posted by GenerationE
    Quote Originally Posted by MagiMaster
    I think the left-to-right bit is a bit confusing. I'm pretty sure as long as you always go clockwise (or counter-clockwise), going back and forth from one end to the other won't matter. Overall, the number of turns should matter most.
    Your right as long as you go the same direction the field won't cancel. It's given by the right had rule point your thumb in the direction of the Current and your fingers should be pointing in the direction of the field at that point. What I think we were all saying is that if you wind it one way around the tube, and then want to add another layer, you may end up canceling the fields out depending on which way you wrap back around. But your correct the only thing that matters is that the current's stay in the same direction.

    I also need to correct my post, it's turn's per meter or per unit length that really matter. So basically then density of the turns, like what Harold had said.

    You can wind a bar like this though, in opposite directions. Like a horse shoe magnet, but opposite to each other. I did this when I was a kid. And I just did it again to check it out. Not that I doubted my memory or anything, ha-ha.

    It does cause the bar to magnetize. Which is interesting because it opens up the door to some other beliefs being wrong.




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    No. Nothing there suggests that the bar shouldn't magnetize. It'd only cancel out if the reversed windings overlap, and then only in the places where they overlap. The way you have that wound, each end should be magnetized (slightly less so than if the other end were removed) and the middle of the bar also be magnetized since the field lines are perpendicular to the bar and overlap there. In a normal winding, the middle wouldn't be particularly magnetic because the field lines would be parallel to the bar.

    Of course, this isn't really my area of expertise, but it's easy enough to try it yourself. Tell us how it goes. Of course, if anyone else thinks my analysis is wrong, feel free to correct me.
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    Quote Originally Posted by Harold14370
    Quote Originally Posted by chekhonte
    That table really helps. I might order some thicker gauge wire and try to push the amps a little bit. I have some rather massive iron rods that I want to try out. 12 inches by 2 1/2 inches cylindrical.
    Be careful how you use those ampacity tables. Those are designed for cable in free air. Your cable is wrapped around on itself, and would have to be derated quite a bit unless you are just energizing it intermittently.

    Before you go down that road of increasing your wire gauge, make a few simple calculations. The magnetic flux will be proportional to the current multiplied by the number of turns. From the diameter of the wires, including the insulation, figure out how many turns will fit on your core with each size wire. Then use the current rating of the wire, and see how many ampere-turns you will get for each wire size with the maximum current in the wire.
    You are correct in that the magnetic field will vary with the number of terms, in fact sometimes the field is measured in "amp turns". But the wire size only limits the number of turns per layer, and you can always add layers. There is also a limit when you saturate the core, and things go very non-linear.

    De-rating of the coil is necessary for continuous duty, but for a brief period of time the ratings of the conductors in the table would be pretty good -- avoids a prompt melt-down of the insulation. That was the point of my paragraph on heat transfer.
    If an IR thermometer is used to monitor the temperature of the outside coils, things ought to be OK for short-term current flow.

    The good news is that even if the heat gets high, unless there are flammable vapors around, the damage will be simply melting some insulation and shorting out the coil. Maybe blow a breaker. Fortunately coils and wire are not too valuable.

    It might be better if the experiment were done with an AC power source. Then the inductance of the coild would add some additional impedance to limit the current. But it would be a bit more difficult to measure the magnetic field since it would be time-varying.

    Although you might use "magnet wire" I would be careful with it. That stuff generally has a very thin and sometimes brittle insulation. That permits a lot of turns in small volume, which is efficient, but it is also rathe susceptible to damage from heat if you get the current a bit high. It is usually used to wind coils for things like AC motors and transformers, and there you usually benefit of current limitation by inductance. If you use enough wire of small gauge you can also get enough resistance to limit current as well, but you need to wind a lot of wire to do that.

    It helps to use soft iron for the core, as opposed to a piece of steel in order to maximize the magnetic flux.
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  32. #31 winding a solenoid 
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    Well this forum was posted 2 years ago but just in case you haven't figured it out.
    i am going to start experimenting with solenoids myself. my theory (although not yet proven) is that when you wind the solenoid from left to right then reach the end (on the right side) start to wind it back from right to left but with as few loops as possible while still keeping tension on the wire.

    what i hope this will do is reduce the amount of juice being canceled out by the returning wire thus giving you a much larger push to pull ratio. i cant start my work for a while. so plz if you give this a try give me some feedback on the results.

    thanx

    Carlos Quintero
    carlos.quintero222@gmail.com
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  33. #32  
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    Carlos,

    The second layer does not cancel out the magnetic field of the first layer. It adds to it, unless you start wrapping the opposite way around the core. For example, you wouldn't want to make the first layer clockwise and the second counterclockwise.
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  34. #33  
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    It is clear that if you would change the winding direktion that it doesn,t work. Energy-loss and if the amount of windings for both direktions would be the same it would cancel out completely...a loss of about hundred-procent.

    But would turning the winding direktion in the sence of winding from one end to the other (of the core) have influence ?

    You could have two coils around a core of same diameter but one core twice as long as the other. If both cores have the same amount of windings and are completely filled the shorter core has two layers whereas the longer one has only one.

    Theoretically it makes no difference but in practice I think it does (or must) make a difference at least I would want to see it confirmed in practice that it does not make a difference (that it makes no difference).

    A posible way to approach it could be that the volume of both coils and cores is different.
    The larger the core the more loss it could give. Or the less corematerial the larger the loss as it would heat up more. the surface of both coils is different also. The longer coil would stay cooler as it has more surface to cool. Hence the corematerial could change it,s properties and resistance. More or less loss in the core. How significant that is in practice for a certain purpose is another question.
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  35. #34  
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    Quote Originally Posted by Harold14370
    Carlos,

    The second layer does not cancel out the magnetic field of the first layer. It adds to it, unless you start wrapping the opposite way around the core. For example, you wouldn't want to make the first layer clockwise and the second counterclockwise.
    Which is reflected in the somewhat common measurement of magnetic fields as "amp turns".
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  36. #35 Solenoid project 
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    Wow, I think I've enjoyed the electromagnet readings and videos thus far. I am working on building my first solenoid with an iron core and I am a little stuck I am practicing with a few numbers. My core is 6in and core diameter is 1.5in and I have a 24 wire gauge. I am using a 2 Amp current supply. What is the best way for me to figure out the number of layers of my wire? I know this is probably a simple problem and I've been working on this for about a week now lol... Thanks for any help!
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