electromagnet question for the tech gurus

[MrDudeMan]

i would post this in high tech but it would get locked...

and this is the only other place where lots of people frequent the forums and there are some smart cookies...


so here it goes



i am making a project that involves some really strong e-mag's

it is a chair or sorts that levitates and can hold up a person




it needs to be able to support between 150 and 300 pounds (easily) and maybe 350-400 absolute tops, but more the middle range


anyways, it is a fairly easy project and if you are interested, PM me and ill send you pics and such as they turn up, but what i need to know is what kind of magnets to get to make this possible


i found this site that has TONS of e-mags that require hardly any power, but it seems WAY too good to be true

here is a good site i found with some magnets (the ones you are pointed to are round...if you click on the left menu you can get to other types of e-mag's and if you go all the way back to other magnets, but im not really interested in those)


according to this chart i should be able to get the ER(1-3)-503 series which can hold 600+ pounds at just under 50w of power and the net weight is 13lbs

that seems like way too much lifting power for only 50w of power...someone help me out here!

 

[dighn]

Originally posted by: MrDudeMan
i would post this in high tech but it would get locked...


according to this chart i should be able to get the ER(1-3)-503 series which can hold 600+ pounds at just under 50w of power and the net weight is 13lbs

that seems like way too much lifting power for only 50w of power...someone help me out here!

dunno too much about these industrial things but theoretically given any power you can have as much lifting power as you want because the lifiting power is a function of the magnetic field which is a function of the current not the power



i dont know if your levitation idea would work though, what is your idea of goinga bout it anyway?

 

[MrDudeMan]

im fairly sure it will work. i have been discussing it for quite some time now with my physics teacher (he is a pretty smart dude. dunno all of this qualifications

and what not, but i know he is really smart). anyways, it involves a seat with one of these magnets on the inside with north pointing toward the floor. it then

has little rollers/magnets lining the inside lip which will hang down over the bottom part of the chair. the bottom part will have another of these huge

magnets with north pointing up to repel the seat. the sides of the seat part will be flanged in a way that it wont slide off from side to side and probably have

some sort of track so it wont fly up either. it will have power cords on the inside on a track, not wires, so they dont tangle no matter how many times you

spin around.


sorry, i know this isnt very clear, but its rather hard to explain w/o a chalkboard


edit: i know how magnets work and i know fields are generated with current, but current is part of power, and the power has a lot to do with it depending on the voltage applied.

 

[dighn]

Originally posted by: MrDudeMan
im fairly sure it will work. i have been discussing it for quite some time now with my physics teacher (he is a pretty smart dude. dunno all of this qualifications

and what not, but i know he is really smart). anyways, it involves a seat with one of these magnets on the inside with north pointing toward the floor. it then

has little rollers/magnets lining the inside lip which will hang down over the bottom part of the chair. the bottom part will have another of these huge

magnets with north pointing up to repel the seat. the sides of the seat part will be flanged in a way that it wont slide off from side to side and probably have

some sort of track so it wont fly up either. it will have power cords on the inside on a track, not wires, so they dont tangle no matter how many times you

spin around.


sorry, i know this isnt very clear, but its rather hard to explain w/o a chalkboard

oh i see so there is something to mae it stable. sure that wouldnt be a problem

i thought u wanted to go for a pure leviation with no physical support which would complicated to do

 

[MrDudeMan]

Originally posted by: dighn

Originally posted by: MrDudeMan
im fairly sure it will work. i have been discussing it for quite some time now with my physics teacher (he is a pretty smart dude. dunno all of this qualifications

and what not, but i know he is really smart). anyways, it involves a seat with one of these magnets on the inside with north pointing toward the floor. it then

has little rollers/magnets lining the inside lip which will hang down over the bottom part of the chair. the bottom part will have another of these huge

magnets with north pointing up to repel the seat. the sides of the seat part will be flanged in a way that it wont slide off from side to side and probably have

some sort of track so it wont fly up either. it will have power cords on the inside on a track, not wires, so they dont tangle no matter how many times you

spin around.


sorry, i know this isnt very clear, but its rather hard to explain w/o a chalkboard

oh i see so there is something to mae it stable. sure that wouldnt be a problem

i thought u wanted to go for a pure leviation with no physical support which would complicated to do

hehe yeah that would be awesome though

what do you think about those e-mags in that link though? seems like i was able to find them way too easily and they are perfect...hmm

 

[dighn]

true current is part of power but it's inverse to voltage for a fixed wattage. now those magnets run on 12/24 dc, for 50 watts that's ~ 2-5 amps of current which is a lot of current

if they say it works... i dunno it should work? LOL. 2-5 amps is a lot, i'm more towards believing it can hold that much weight

edit:

the * beside the weight say * Holding values stated are under ideal conditions rated at 50% of the actual value.

wth is that supposed to mean

 

[MrDudeMan]

Originally posted by: dighn
true current is part of power but it's inverse to voltage for a fixed wattage. now those magnets run on 12/24 dc, for 50 watts that's ~ 2-5 amps of current which is a lot of current

if they say it works... i dunno it should work? LOL. 2-5 amps is a lot, i'm more towards believing it can hold that much weight

yeah i mean 5 amps is a sh!tload of power for a magnet but STILL i mean 600#? wow if this works...

 

[Gillbot]

to hold up that much weight it will need a bit of power. The problem you may run into is if you build it to hold 300lbs, and a lighter person sits in it, it may not be as stable and vice versa.

 

[MrDudeMan]

well we are going to use stabilizers

around the ouside lip of the seat there will be magnets with north pointing inside and around the base there will be more small magnets with north pointing outside, so the seat will be repelled upward and outward, causing it to stay in the center (mostly) and then we are going to (somehow, not sure yet) attach the seat so it cant fly off upward when it is powered up and there is no load besides the net weight of the seat.

 

[MrDudeMan]

if someone lighter sits, it just wont sink as much. i am going to design it for roughly 250# (or around my weight). i think the max it will be able to hold is WAY more than that, but we shall see.

 

[compudog]

If you are using DC magnets in the lower voltage range you should be able to build a power supply to vary the current for different loads. This is the easiest type of power supply to put together. Perhaps a modified DC motor drive could be adapted to power the magnets, because a DC motor is just a magnet of sorts.

 

[MrDudeMan]

Originally posted by: compudog
If you are using DC magnets in the lower voltage range you should be able to build a power supply to vary the current for different loads. This is the easiest type of power supply to put together. Perhaps a modified DC motor drive could be adapted to power the magnets, because a DC motor is just a magnet of sorts.

i thought about doing this but how hard would it be to guage how much it could hold at given current? i could always use a computer PSU because that would be perfect...12v and it can go up to 15A usually...so one could power both, or to be safe i could use 2 computer PSU's...

hmm

 

[compudog]

There is no way to vary the current output of a computer PSU without modification. There are a couple ways you can vary the current with a DC drive though, as for how much a given output can support, you would need to develop a scale by trial and error. Say you had a total load of 5 amps DC at 24 volts, you could set the control pot to full and it would support the max of 500 pounds. Then you could set the control pot to 50% and it would have an output of 2.5A and support, say 150 pounds. I don't think it would be a truly linear or easily computable curve. Anyway, once you do your trial and error, you could label the know, at it's various positions, for the weight that would be supported. As for determining the amps, you could use a digital multi meter or a dedicated ampmeter. Most of the stuff could be found online or at an industrial supply house.

 

[MrDudeMan]

Originally posted by: compudog
There is no way to vary the current output of a computer PSU without modification. There are a couple ways you can vary the current with a DC drive though, as for how much a given output can support, you would need to develop a scale by trial and error. Say you had a total load of 5 amps DC at 24 volts, you could set the control pot to full and it would support the max of 500 pounds. Then you could set the control pot to 50% and it would have an output of 2.5A and support, say 150 pounds. I don't think it would be a truly linear or easily computable curve. Anyway, once you do your trial and error, you could label the know, at it's various positions, for the weight that would be supported. As for determining the amps, you could use a digital multi meter or a dedicated ampmeter. Most of the stuff could be found online or at an industrial supply house.

by using a computer power supply...i meant use the 12v line and put a POT on it...that will definitely limit the current on it. i know it will because i have done it. but i see what you mean about the rest of it and it makes good sense. i appreciate your ideas and will probably utilize your trial and error technique in my project.