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does anyone know how to create an electromagnet that draws its power from AC current instead of DC? I want to create a large electromagnet (maybe make it portable also) A good program is a well commented one - Aaron Sulwer

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AC or DC, you build them the same way. Comments don't define how well a program works - Matthew Daughtrey -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 1:08 PM To: ' Subject: [BasicX] electromagnet does anyone know how to create an electromagnet that draws its power from AC current instead of DC? I want to create a large electromagnet (maybe make it portable also) A good program is a well commented one - Aaron Sulwer

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>AC or DC, you build them the same way. Should I use a special gauge wire? I cannot just wrap a wire around a nail a bunch of times and then apply ac current that would not work. How many times should I wrap the wire and what gauge should I use? >Comments don't define how well a program works - Matthew Daughtrey they help others understand your program thus are a valuable asset to your program making it better. do you see the relationship? There are a lot of programmers out there that don't comment there code and expect others to understand there encrypted way of coding. [Non-text portions of this message have been removed]

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Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 1:47 PM To: ' Subject: RE: [BasicX] electromagnet >AC or DC, you build them the same way. Should I use a special gauge wire? I cannot just wrap a wire around a nail a bunch of times and then apply ac current that would not work. How many times should I wrap the wire and what gauge should I use? >Comments don't define how well a program works - Matthew Daughtrey they help others understand your program thus are a valuable asset to your program making it better. do you see the relationship? There are a lot of programmers out there that don't comment there code and expect others to understand there encrypted way of coding. [Non-text portions of this message have been removed]

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Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed]

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I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed]

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I want to test the effects of magnets on humans. example - I have some strong magnets. when I pass them over my hand I can feel them moving. I feel the magnetic field. At least I think that I do. so if I had a stronger magnet then the field would be stronger thus I would be able to feel it more. I have whatever is coming out of my wall at home - 120 volts AC. I can use a transformer to step this up -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 1:54 PM To: ' Subject: RE: [BasicX] electromagnet I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed] eGroups Sponsor <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ A=564920/*http://www.columbiahouse.com/gateway?token=7407> Get 3 CDs for ONLY $9.99! Get 3 CDs for ONLY $9.99! <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 00005378:N/A=564920/rand=351510966 [Non-text portions of this message have been removed]

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Aaron- There is likely to be a vast literature on electromagnetic effects on humans due to the extensive use of MRI technology in the medical field- you might try a literature search on PubMed (www.ncbi.nlm.nih.gov/entrez). For your own experiments, you might look into a place like Edmund Scientific as a source for powerful electromagnets. Good luck! peter Peter C. Charles, Ph.D. Research Assistant Professor Department of Microbiology and Immunology Rm. 730 Mary Ellen Jones Building, CB# 7290 UNC Chapel Hill, NC 27599-7290 Caesar si viveret, ad remum dareris. -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 3:32 PM To: ' Subject: RE: [BasicX] electromagnet I want to test the effects of magnets on humans. example - I have some strong magnets. when I pass them over my hand I can feel them moving. I feel the magnetic field. At least I think that I do. so if I had a stronger magnet then the field would be stronger thus I would be able to feel it more. I have whatever is coming out of my wall at home - 120 volts AC. I can use a transformer to step this up -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 1:54 PM To: ' Subject: RE: [BasicX] electromagnet I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed] eGroups Sponsor <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ A=564920/*http://www.columbiahouse.com/gateway?token=7407> Get 3 CDs for ONLY $9.99! Get 3 CDs for ONLY $9.99! <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 00005378:N/A=564920/rand=351510966 [Non-text portions of this message have been removed]

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If we were that sensitive to magnetic fields then MRIs would just be killing people. Give yourself a double-blind test; have a friend cover one magnet and another object with identical sheets of paper without you seeing so you can't tell which is which. Do this test 10 or 20 times and note the results. The more tests you do the closer your guesses will be 50% one paper, 50% the other. -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 3:32 PM To: ' Subject: RE: [BasicX] electromagnet I want to test the effects of magnets on humans. example - I have some strong magnets. when I pass them over my hand I can feel them moving. I feel the magnetic field. At least I think that I do. so if I had a stronger magnet then the field would be stronger thus I would be able to feel it more. I have whatever is coming out of my wall at home - 120 volts AC. I can use a transformer to step this up -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 1:54 PM To: ' Subject: RE: [BasicX] electromagnet I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed] eGroups Sponsor <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ A=564920/*http://www.columbiahouse.com/gateway?token=7407> Get 3 CDs for ONLY $9.99! Get 3 CDs for ONLY $9.99! <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 00005378:N/A=564920/rand=351510966 [Non-text portions of this message have been removed]

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Mathew- Technically speaking, the person who administers the test should also not know which one has the magnet, for it to be truly "double-blind." As an irrelevant aside--I'm not entirely sure that people can't sense magnetic fields. I had an MRI of my head several years ago and was nauseated and disoriented for about 4 hours afterward. This is, of course, entirely anecdotal and an N of 1, but it was quite striking. peter Peter C. Charles, Ph.D. Research Assistant Professor Department of Microbiology and Immunology Rm. 730 Mary Ellen Jones Building, CB# 7290 UNC Chapel Hill, NC 27599-7290 Caesar si viveret, ad remum dareris. -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 4:05 PM To: ' Subject: RE: [BasicX] electromagnet If we were that sensitive to magnetic fields then MRIs would just be killing people. Give yourself a double-blind test; have a friend cover one magnet and another object with identical sheets of paper without you seeing so you can't tell which is which. Do this test 10 or 20 times and note the results. The more tests you do the closer your guesses will be 50% one paper, 50% the other.

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should I "scramble wrap" the wire on the metal bar? Does that effect the strength of the magnet? I still would like to know what gauge wire would be best. I have 18 gauge (I think). I have about 12 pounds of it. Is there anything I can do to improve the field strength? -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 3:05 PM To: ' Subject: RE: [BasicX] electromagnet If we were that sensitive to magnetic fields then MRIs would just be killing people. Give yourself a double-blind test; have a friend cover one magnet and another object with identical sheets of paper without you seeing so you can't tell which is which. Do this test 10 or 20 times and note the results. The more tests you do the closer your guesses will be 50% one paper, 50% the other. -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 3:32 PM To: ' Subject: RE: [BasicX] electromagnet I want to test the effects of magnets on humans. example - I have some strong magnets. when I pass them over my hand I can feel them moving. I feel the magnetic field. At least I think that I do. so if I had a stronger magnet then the field would be stronger thus I would be able to feel it more. I have whatever is coming out of my wall at home - 120 volts AC. I can use a transformer to step this up -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 1:54 PM To: ' Subject: RE: [BasicX] electromagnet I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed] eGroups Sponsor < http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ > A=564920/* http://www.columbiahouse.com/gateway?token=7407 <http://www.columbiahouse.com/gateway?token=7407> > Get 3 CDs for ONLY $9.99! Get 3 CDs for ONLY $9.99! < http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 > 00005378:N/A=564920/rand=351510966 [Non-text portions of this message have been removed] eGroups Sponsor <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ A=564956/*http://www.columbiahouse.com/gateway?token=7415> Choose 3 DVDs for $0.49 each! Choose 3 DVDs for $0.49 each! <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 00005378:N/A=564956/rand=143503023 [Non-text portions of this message have been removed]

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To obtain the strongest field possible you need wrap the wire on the iron bar very neatly Side-by-side from one end to the other. Once you reach the end start a new layer directly above the first and work to the other end (And so on and so on). You should only use enameled wire and insulate the iron bar with a thin piece Of plastic prior to wrapping it. Once your done test it with a D cell battery. If it works then try incrementally larger Amounts of voltage. If the iron bar or wire starts getting hot cut back your voltage. The best gauge for what you want to do is around 22 - 28. 18 gauge will be hard to wrap and tend to spring out of place. ---------- From: Aaron Sulwer [SMTP:] Sent: Wednesday, January 24, 2001 2:54 PM To: ' Subject: RE: [BasicX] electromagnet should I "scramble wrap" the wire on the metal bar? Does that effect the strength of the magnet? I still would like to know what gauge wire would be best. I have 18 gauge (I think). I have about 12 pounds of it. Is there anything I can do to improve the field strength? -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 3:05 PM To: ' Subject: RE: [BasicX] electromagnet If we were that sensitive to magnetic fields then MRIs would just be killing people. Give yourself a double-blind test; have a friend cover one magnet and another object with identical sheets of paper without you seeing so you can't tell which is which. Do this test 10 or 20 times and note the results. The more tests you do the closer your guesses will be 50% one paper, 50% the other. -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 3:32 PM To: ' Subject: RE: [BasicX] electromagnet I want to test the effects of magnets on humans. example - I have some strong magnets. when I pass them over my hand I can feel them moving. I feel the magnetic field. At least I think that I do. so if I had a stronger magnet then the field would be stronger thus I would be able to feel it more. I have whatever is coming out of my wall at home - 120 volts AC. I can use a transformer to step this up -----Original Message----- From: Matthew Daughtrey [mailto:] Sent: Wednesday, January 24, 2001 1:54 PM To: ' Subject: RE: [BasicX] electromagnet I'll take the sig thread offline. Re the electromagnet, this is OT and you might be better served with a web search or the sci.electronics.* newsgroups. If you want to keep it here, tell us your application. How much lifting surface area do you need, or is this more like a solenoid design where you want to pull metal through the coil? What voltage and current do you have to work with? -----Original Message----- From: Aaron Sulwer [mailto:] Sent: Wednesday, January 24, 2001 2:36 PM To: ' Subject: RE: [BasicX] electromagnet Wire gauge and turns are going to depend on your application and how much force you want to generate, so more details would be useful. I would like to be able to lift about 25-50 lbs. There's a difference between a program being made good because of comments (which is what you are saying) and a program being made *better*. If you're going to have the hubris to quote yourself, come up with something defensible. since you are critiquing my signature maybe you can help me come up with a better way of getting my point across? [Non-text portions of this message have been removed] eGroups Sponsor < http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ > A=564920/* http://www.columbiahouse.com/gateway?token=7407 <http://www.columbiahouse.com/gateway?token=7407> > Get 3 CDs for ONLY $9.99! Get 3 CDs for ONLY $9.99! < http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 > 00005378:N/A=564920/rand=351510966 [Non-text portions of this message have been removed] eGroups Sponsor <http://rd.yahoo.com/M=168002.1291681.2888959.2/D=egroupmail/S=1700005378:N/ A=564956/*http://www.columbiahouse.com/gateway?token=7415> Choose 3 DVDs for $0.49 each! Choose 3 DVDs for $0.49 each! <http://us.adserver.yahoo.com/l?M=168002.1291681.2888959.2/D=egroupmail/S=17 00005378:N/A=564956/rand=143503023 [Non-text portions of this message have been removed]

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>AC or DC, you build them the same way. Not quite, you don't have to worry about eddy currents in the cores of DC electromagnets. AC electromagnets MUST have laminated cores, DC ones can be on solid steel cores. Also, your armature should be laminated for AC solenoids to avoid inducing eddy currents in that. Magnetic saturation can also be a problem in AC work.... Depending on what you want to do, you might find there's a line powered electromagnet powerful enough in your washing machine (typically there's one that controls the hot/cold water valve or applies/releases the brakes on the drum). I had one that was about 2 inches cubed (including armature), and it'd take your finger off without batting an eyelid [talk about mixed metaphors!]. If you kept the armature away from the core with something very strong but non magnetic (eg a bit of solid plastic), you could get the house lights to dim appreciably when you first turned it on! My favourite trick was to sit it on the floor, under someone's chair with the armature pulled about 3/4 the way out. Wait until the 'victim' sat down, and hit the power. The very loud metallic "CLACK" that ensued as the armature snapped in was enough to get a real jump out of the victim! [Warning: DON'T TRY THIS AT HOME unless you really know what you're doing. I went to extreme measures to make sure that there was NO way any mains voltages could escape. Heatshrink tubing, electrical tape, and several ounces of silicone rubber...] Lost it somewhere either in a cleanup or a move, and have missed it ever since. (The wife gives me "that look" every time I go near our washer with a screwdriver in hand,... :-). >Comments don't define how well a program works - Matthew Daughtrey Neither does Management, but somehow the programmer still has to write it. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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> >AC or DC, you build them the same way. > >Should I use a special gauge wire? I cannot just wrap a wire around a nail >a bunch of times and then apply ac current that would not work. How many >times should I wrap the wire and what gauge should I use? If you can't answer these questions yourself, please tell me you're NOT building a "line" (that is direct to the mains) powered solenoid. If you get it wrong, or get a small 'nick' in the insulation, the whole thing could be at line potential, and that'd be very dangerous. What is the intended application? There might very well be a solenoid that could be salvaged from a household appliance (or even bought as a "spare part") that would be ready made for you. As I said in antoher post, you can't use a single piece of steel for AC solenoids,... you'd be effectively making a transformer with a shorted secondary and things'll get very hot! > >Comments don't define how well a program works - Matthew Daughtrey >they help others understand your program thus are a valuable asset to your >program making it better. do you see the relationship? There are a lot of >programmers out there that don't comment there code and expect others to >understand there encrypted way of coding. He was pulling your leg!! :^) David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>Wire gauge and turns are going to depend on your application and how much >force you want to generate, so more details would be useful. > >I would like to be able to lift about 25-50 lbs. Wow!! I know some folks who have trouble lifting that with their bare arms...! (that's 10 to 20 kilograms or so, right?) Over what range do you want to 'lift' that weight? Sounds like you'd be far better off with a motor and gearbox than an electromagnet. How 'bout you tell us the whole project and let us offer (safer) alternatives.... enough mains power to electromagnetically lift that kinda weight is not the sort of thing you want to be doing if you don't already know very much more about it than you do... >since you are critiquing my signature maybe you can help me come up with a >better way of getting my point across? How about "Document it properly or I beat you with a big stick"?? Seriously, documentation is a very sore point. All programmers worth their salt know it has to be done, and most agree it has to be done better. But if management gives you a 2 week deadline for a job that would take 6 weeks including documentation, what do you think gets sacrificed first? And how much do you value your job? Can you say to your boss, no I refuse to do this project because you haven't allowed enough time to document it properly? And, further, the documentation doens't just apply to code either, you should really be documenting the whole "waterfall", that is, from concept, to feasability study (if required), to initial product(customer?) requirements, to system design, to detailed design, to design verification, to selection of platform/language/tools etc. and lastly, to coding and implementation.... How do you capture THAT in a one line sig? _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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At 10:37 AM 1/25/01 +0800, you wrote: >> >AC or DC, you build them the same way. <---The windings for an AC or DC solenoid are the same, true, However, the core (that the windings are on, not the armature, or moveable part) construction between the two are very different. An AC solenoid typically requires a physical "shunt" of sorts, in order to keep the armature from buzzing. But since you're dealing with a DC coil, you may find the following useful: The relative force generated by a coil is measured in ampere-turns, or simply the current through the winding times the number of turns. This can be expressed as: N2/R=k where N = the number of turns where R = the resistance per cubic inch of winding where k = the area of the winding. This may be more information than you need, but you may find it helpful, especially if you're a math type <g> Ken ------------------------------------------------------------------------------ Ken Arck - Senior Unix Systems Analyst Meridian Technology Group http://www.meridiangroup.com http://www.ah6le.net Amateur Radio Station AH6LE palace://stables.xsia.com:9998 aka Ph's horse

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>I want to test the effects of magnets on humans. example - I have some >strong magnets. when I pass them over my hand I can feel them moving. I'm going to put this disclaimer up the top, in case you get bored reading the rest of this. PLEASE CONSIDER WHAT YOU'RE DOING VERY CAREFULLY. If you _do_ still want to do this after you read all my ramblings, I'd strongly suggest you have a qualified electrician and someone who can apply emergency medical treatment on hand when you try this out. I'm not kidding, if you're talking this much magnetism and mains power outlets, you really wanna look out for yourself. Now, having said, that, here's what I feel happy offering (I do know more, but I'm not willing to pass it on, since I don't want to feel responsible for what might happen). I _STRONGLY_ Suggest you read up a lot of material on Computer Tomography before you go cookin' yourself!! There's much material already written about the results of such testing, and the techniques used to do the tests. (Although not much on actually building the stuff,... I guess "Back yard Cat scanners in 10 easy steps" just isn't a best seller...) >I feel the magnetic field. At least I think that I do. Very difficult to be conclusive about, since you're about as far away from a double-blind test as you can be.... You need to get someone to make a series of identical boxes for you, and put strong permanent magnets, weak permanent magnets, and lumps of non-magnetic material in various ones, so that they're all the same weight, size, shape colour etc. and only the guy that makes the boxes knows which ones are magnetic. Now, you put a blindfold on for the rest of the tests, until I say you can take it off :-) Then you get the guy who made the boxes to hand the boxes one at a time in some random order to another guy who doesn't know which ones are which (and make sure that he's not wearing anything that's ferrous otherwise he's gonna figure out which ones are which!) Now, this second guy waves a box over your hand in such a way that you don't know when he's waving it and when he's not. (Maybe you should have earmuffs on too, gee, you're lookin' kinda silly now, huh? :-). As soon as you think you feel something (other than the breeze when he's moving his hand!) you say so. No-one else says anything or makes any other sound, but the another (fourth?) person who has no idea what's in the boxes and is watching through a window (so you can't hear them writing) writes a tick or cross on a piece of paper as to whether you said anything. As each box is tested it is marked with a number so that you can tie the ticks and crosses up with the boxes. Then after all the boxes are done, you take off your blindfold and earmuffs and then spend the next few hours sorting out all the boxes, ticks, crosses, and open the boxes to find out if they've got magnets in'em. Note that you'd have to do at least 100 tests (maybe you can cycle a smaller number of boxes over a few times) to get even close to a statistically significant result. The important things are that 1) the person waving the boxes over your hand can't know what's in them. 2) you can't tell when they're waving them over your hand. 3) the person marking the ticks/crosses can't tell what's in the boxes (no cheating please!). 4) no-one says or does anything that you can detect that would affect your 'feeling'. >so if I had a >stronger magnet then the field would be stronger thus I would be able to >feel it more. Yes, but are you aware of any negative effects of extra-strong electromagnetic fields on humans? Are you aware that there's a growing feeling of concern about people who are forced to live under or near high voltage power lines, even though the electric companies insist that they can't find any measurements that indicate it's not safe? (Yes I know this is electric fields, and you're talking magentic ones, but how can you be sure?). >I have whatever is coming out of my wall at home - 120 volts AC. at 20Amps or so, ... do you _know_ how quickly that can kill you if misapplied? >I can use a transformer to step this up I'd be much happier if you used a transformer to step it DOWN... Magnetic field is proportional to current, not voltage. So you want lots of amps, To get them out of your outlet, you need to drop the voltage. Eg, an electric welding supply takes in mains, and puts out at least 200Amps, but probably at 2 or three volts. A few turns of insulated curtain rod around something very ferrous would make a damned fine electromagnet (at least until the curtain rod melted :-). One final question,... are you sure you haven't had surgery that your folks haven't told you about, and say, had a pin put in a broken bone or something?? I'd hate for you to find out by ramping up the magnetic field stronger and stronger until the pin pops out of your hand!!! David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>If we were that sensitive to magnetic fields then MRIs would just be >killing >people. Give yourself a double-blind test; have a friend cover one magnet >and another object with identical sheets of paper without you seeing so you >can't tell which is which. Do this test 10 or 20 times and note the >results. The more tests you do the closer your guesses will be 50% one >paper, 50% the other. That's not a double blind test. The friend knows which ones are magnets and which ones aren't! Double blind means that neither the "tester" or the "testee" knows which ones are real. That way, the testee can't pick up on any external stimulii from the tester. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>should I "scramble wrap" the wire on the metal bar? Does that effect the >strength of the magnet? I still would like to know what gauge wire would >be >best. I have 18 gauge (I think). I have about 12 pounds of it. Is there >anything I can do to improve the field strength? Dear God I hope I'm not too late. PLEASE STOP what you're doing and do much more research before you go plugging a scramble-wrapped pile of 18 guage wire wrapped around a non-laminated bar into a power outlet... (Please tell me this guy's got earth leakage breakers fitted in his house)... I'm serious. Many people have ended up dead playing with stuff like this, even some that thought they knew what they were doing.... David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>To obtain the strongest field possible you need wrap the wire on the iron >bar >very neatly Side-by-side from one end to the other. Once you reach the end >start a new layer directly above the first and work to the other end (And >so >on and so on). > >You should only use enameled wire and insulate the iron bar with a thin >piece >Of plastic prior to wrapping it. > >Once your done test it with a D cell battery. If it works then try >incrementally larger >Amounts of voltage. If the iron bar or wire starts getting hot cut back >your >voltage. Sound advice,... for a DC electromagnet. Don't use a solid Iron bar for an AC one. >The best gauge for what you want to do is around 22 - 28. 18 gauge will be >hard >to wrap and tend to spring out of place. Not true at all. The field strength is proportional to both current and turns... To get the highest field strength, you need high current (thick wire) and many turns... That's why all the really powerful electromangets (like in particle accelerators and the like) are made from (typically) copper tubing, that way they can pass massive currents through the copper, and cooling fluid through the inside of the pipes! But, as I said before. Unless you really know what you're doing, you shouldn't be building ANYTHIGN that runs straight off line voltages and currents.... It's just not safe. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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I stand corrected. -----Original Message----- From: David Emrich [mailto:] Sent: Wednesday, January 24, 2001 10:06 PM To: Subject: RE: [BasicX] electromagnet >If we were that sensitive to magnetic fields then MRIs would just be >killing >people. Give yourself a double-blind test; have a friend cover one magnet >and another object with identical sheets of paper without you seeing so you >can't tell which is which. Do this test 10 or 20 times and note the >results. The more tests you do the closer your guesses will be 50% one >paper, 50% the other. That's not a double blind test. The friend knows which ones are magnets and which ones aren't! Double blind means that neither the "tester" or the "testee" knows which ones are real. That way, the testee can't pick up on any external stimulii from the tester. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>At 10:37 AM 1/25/01 +0800, you wrote: > >> >AC or DC, you build them the same way. > ><---The windings for an AC or DC solenoid are the same, true, However, the >core (that the windings are on, not the armature, or moveable part) >construction between the two are very different. > >An AC solenoid typically requires a physical "shunt" of sorts, in order to >keep the armature from buzzing. But since you're dealing with a DC coil, I'm not dealing with any coils, however, the original poster specifically wanted a coil he could run direct of his mains power point. THAT has to be done with some care. And how can the armature not suffer eddy current losses if the field is changing at 50 or 60Hertz?? I'm prety sure the armature must also be laminated in an AC drive solenoid. >you may find the following useful: > >The relative force generated by a coil is measured in ampere-turns, Nope, force is measured in Newtons... Ampere-turns come about because the force is proportional to both the current and number of turns. However the final motive force depends on core and coil geometry, armature geometry as well as material constants (permeability or something isn't it?) >N2/R=k > >where N = the number of turns >where R = the resistance per cubic inch of winding >where k = the area of the winding. The resistance part only serves to limit the DC current. That formula has it's uses but does not help in computing the force available to do work. The one I remember at least partially is something like F = nBIL / (something?) F is force n is number of turns I = current L = length of coil (something) is an expression involving the outer diameter of the core B is a material constant of the core. However that's a very long time ago, and I'm not sure I'm not mixing a couple (or more) formulae all into one. In theory, one could derive it all from Maxwell's equations, but I'm not going to. :-) David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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>I stand corrected. But we only have your word on that. We'd need an independent witness who wasn't aware of the history behind that comment to verify it! :-) PS: it's much more comfortable to sit corrected.... D. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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Good point! I'll arrange the webcam immediately. -----Original Message----- From: David Emrich [mailto:] Sent: Thursday, January 25, 2001 12:12 AM To: Subject: RE: [BasicX] electromagnet >I stand corrected. But we only have your word on that. We'd need an independent witness who wasn't aware of the history behind that comment to verify it! :-) PS: it's much more comfortable to sit corrected.... D. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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Yes bigger wire is better but- All I was tying to say is you will have a hard time getting the appropriate number of turns from 18 gauge Wire. While it's true larger gauge wire with the same number of turns will generate a stronger field it is much easier to use smaller wire and more turns to obtain the same effect. I'd hate to be the one wrapping 900 turns of 18 gauge wire around an iron bar. AC? Don't plug this thing into the wall!!! You will wind up hurting or killing yourself. Do yourself a favor and stick with low voltage DC until you can find somebody that knows what they are doing to help you. >To obtain the strongest field possible you need wrap the wire on the iron >bar >very neatly Side-by-side from one end to the other. Once you reach the end >start a new layer directly above the first and work to the other end (And >so >on and so on). > >You should only use enameled wire and insulate the iron bar with a thin >piece >Of plastic prior to wrapping it. > >Once your done test it with a D cell battery. If it works then try >incrementally larger >Amounts of voltage. If the iron bar or wire starts getting hot cut back >your >voltage. Sound advice,... for a DC electromagnet. Don't use a solid Iron bar for an AC one. >The best gauge for what you want to do is around 22 - 28. 18 gauge will be >hard >to wrap and tend to spring out of place. Not true at all. The field strength is proportional to both current and turns... To get the highest field strength, you need high current (thick wire) and many turns... That's why all the really powerful electromangets (like in particle accelerators and the like) are made from (typically) copper tubing, that way they can pass massive currents through the copper, and cooling fluid through the inside of the pipes! But, as I said before. Unless you really know what you're doing, you shouldn't be building ANYTHIGN that runs straight off line voltages and currents.... It's just not safe. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.

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does anyone know what they are doing and can help? thanks everyone for helping me with this OT question ----- Original Message ----- From: Chris Harriman To: ' Sent: Thursday, January 25, 2001 11:20 AM Subject: RE: [BasicX] electromagnet Yes bigger wire is better but- All I was tying to say is you will have a hard time getting the appropriate number of turns from 18 gauge Wire. While it's true larger gauge wire with the same number of turns will generate a stronger field it is much easier to use smaller wire and more turns to obtain the same effect. I'd hate to be the one wrapping 900 turns of 18 gauge wire around an iron bar. AC? Don't plug this thing into the wall!!! You will wind up hurting or killing yourself. Do yourself a favor and stick with low voltage DC until you can find somebody that knows what they are doing to help you. >To obtain the strongest field possible you need wrap the wire on the iron >bar >very neatly Side-by-side from one end to the other. Once you reach the end >start a new layer directly above the first and work to the other end (And >so >on and so on). > >You should only use enameled wire and insulate the iron bar with a thin >piece >Of plastic prior to wrapping it. > >Once your done test it with a D cell battery. If it works then try >incrementally larger >Amounts of voltage. If the iron bar or wire starts getting hot cut back >your >voltage. Sound advice,... for a DC electromagnet. Don't use a solid Iron bar for an AC one. >The best gauge for what you want to do is around 22 - 28. 18 gauge will be >hard >to wrap and tend to spring out of place. Not true at all. The field strength is proportional to both current and turns... To get the highest field strength, you need high current (thick wire) and many turns... That's why all the really powerful electromangets (like in particle accelerators and the like) are made from (typically) copper tubing, that way they can pass massive currents through the copper, and cooling fluid through the inside of the pipes! But, as I said before. Unless you really know what you're doing, you shouldn't be building ANYTHIGN that runs straight off line voltages and currents.... It's just not safe. David. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. eGroups Sponsor www. [Non-text portions of this message have been removed]

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