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Electromagnet Help! How to Make a Small but very Strong Electromagnet???

I need you help smart people of Instructables!
I need to make a small Electromagnet, that uses minimum power (by that I mean the battery), but still has to be very powerful. I have a couple of questions that I need you to help me answer:
  • Does the number of coils that is wound to the metal bar effect the strenght of the electromagnet?
  • Does the wire gauge (20,24,28,30,34,36 wire gauge) make a difference is the strenght of the magnet?
  • Does the voltage I supply to the coil effect the Electromagnet?
  • What type of battery is best for an Electromagnet (AA, AAA, C, D), and what voltage (1,5V, 3V, 4,5V, 6V, 9V) ???

Here is the thing, I need to make the Electromagnet super strong but taking up the minimum of energy, for example, just 1,5V. The things that are not important to me (doesn't play a factor in my device) is the number of wire winds to the metal rod and the wire gauge!

So is it better to just make 1 or more (3,4,5,6...) layers of wire winds???
Is it better to use thinner (36 gauge) or thicker wire (24 gauge)???

Thank you a lot!
Stanislav

yaly2 years ago
too little coil will short the battery and they both eventually heat up too much and it drains the battery . wind neatly in only one direction use the thinnest wire you can find, wind several layers, use 6 D cells in series to produce 9v with enough ampere, you can use a simple method to calculate how much wire you need use a 10Kohm variable resistor and connect the middle terminal to the positive and the left to the negative use your hand to feel the temperature of the battery rotate the pot fully clockwise and then slowly rotate it anti-clockwise until the battery starts to get warm rotate it clock wise again until it stop increasing temperature, disconnect it and measure the resistance with a multimeter and wind the coil to that resistance the length of the coil must be short and the width must be long.
what is the right balance between resistance and current to save battery but get most magnetism. and if you have to get more turns around the spindle, there seems to be a balance issue for how thick you would like the wound spindle to be, i.e. how far away from the spindle the outer windings are and just lengthening the spindle.

it seems to me that while you can't wind thicker wire as tight you get less resistance from thicker wire so your are creating less of a heating element. and the heating would consume current. maybe this is a tradeoff between the ability to make close winds on a spindle with thinner wire even though it creates more load.

on the other hand, very little resistance means a lot of current will flow so you make more heat of a shorter or thicker wire on that basis even though its resistance is not high.

if you are not worried about residual magnetism, i.e. don't need the ability to turn the magnet off 100%, are spindle materials (or i'm actually looking material to extend the spindle to flat surface for a flat magnet parallel or perpendicular to the typical spindle, whatever is recommended, thinking trying to make a superstrong refrigerator magnet) that might actually offer enhancement of magnetic grip by developing permanent magnetism -- or possibly alloy/material that enhances the transmission of electromagnetic force.

if occasionally this permanent magnetism needed to be overcome for fine adjustments, i've noticed you can buy permanent magnet welding supports for holding two plates at right angles and you they have knobs for turning the magnets on and off.

thanks for any thoughts.

jwang20 yaly1 year ago
Apologies for randomly resurrecting this, but I have a question: How do you wind neatly in one direction and wind several layers? Once you get to the end of the nail or whatever, wouldn't you have to wind in the other direction to go back to the start?
They don't mean left to right, they mean clockwise/anticlockwise looking from the end.........
do u need the wire to be insulated or does it matter?
Yes, it needs to be insulated, because the electricity would just flow across, and not through the coils. Electricity takes the shortest route, or the path with least resistance.
now im confused. i took some thick copper wire and wound it around a railroad spike around 20 time and atached eac end to a car battery. it got extremely hot but it picked a magnet of mine off the ground from near a foot away. there wasnt any insulation :/ i dont understand how it worked for me
The electro magnet is not what picked the magnet up, it was the magnet that went to the railroad spike because of the iron in it.
this is extremely late but that isnt what happen. the magnet wouldnt pick itself up until about 3 inches away. i had it over a foot away and it didnt pick it up until i had it attached to the battery
Well Pyrotrician95, It must have of had a Thin, Translucent Coating on it Called "Lacquer". Which is a Good insulent for making electromagnets, The most used as well. So i'm guessing you got that wire from inside a Speaker, AC motor, or somthing with moving Parts...
yaly7 months ago
Of course it needs to be insulated, do not use less than one meter in length (wire before being wound), to wrap several layers and in one direction, wrap a layer then go back in a straight line then start another layer there will be a significant bump if you use thick wire, try not to align these bumps, use a soft iron core or an aluminium one so it won't be magnetized after disconnecting power. Please excuse my English.
akornblatt11 months ago
Hi. I'm also trying to build a small powerful electromagnet. I'm planning to convert it into a motor using the magnetic field to spin either a magnetically permeable material, or a permanent magnet. My current parts list consists of a few toroidal iron ferrite cores as well as a large tool steel core, magnetic wire, and about 4 9V batteries. Is there anything else I'm missing? Also, how many winds on the toroids would I need before I can see any really significant magnetic field? Is there anything else I'm missing? Thank you.
Also I kept all the magnetic wiring to 22 gauge.
NachoMahma5 years ago
> Does the number of coils...
. Yes. More = stronger
.
> Does the wire gauge...
. You can wrap smaller wire tighter (the closer the turns, the better). Since you are using 9V or less, the smallest you can get will probably work; as long as it will handle the current at the applied voltage.
.
> Does the voltage...
. Yes. The more voltage applied, the greater the current.
.
> What type of battery is best...
. A larger battery (C and D) will last longer and provide more current.
. Voltage will depend on the resistance (impedance, if using AC) of the coil and ampacity of your wire and battery.
.
  • You can look up the resistance-per-unit-length figure (eg, ohms/foot) for the wire you are using and compute the coil resistance.
  • As others have mentioned, a permeable core will help "focus" the field.
  • Google is your friend. Look for "DIY electromagnet", &c.

I'm also interested in building a strong electromagnet while trying to keep the weight down.

Googling around and I found this website for ...dum-da-da-dum... "Magnet Man" - Rick Hoadley.

The site has lots of science and exepermiments and all the equations you could need.  But check out the page on electromagnets

There's a downloadable "Coildata" spreadsheet to help you with the design - finding the right balance in the variables.

Simply save it to disk, and then open it. Fill in the data needed in the green boxes. It will calculate the length of wire in a coil, the resistance, and get an approximate inductance for an air core if you want to play with some numbers.

The speadsheet's a beast!  I was going  to dig out my old physics textbook and try to figure out the math - glad I found this site before I tried. 
 

thanks bro, it proved needy
comodore (author)  NachoMahma5 years ago
Thanks NachoMahma! It helped...I think I am going to use lots of turns and a very very thin wire...but low voltage like a 1.5 battery or maybe 3V.. Thanks!
whenever i make mine i just wrap the wire arownd a nail and use a 9v battery for the power suply but its not the best way
hussainsk1 year ago
i was prepared to electromagnet 9v battery how much turns required 24 gage wire
I think coil amount does matter
dookie7912 years ago
I would recommend going to a scrap yard and taking apart a 2-3 ton refrigeration unit and then dissasemble the fan motor. And look at that! Four to five electromagnets are in there, just waiting for you to use them.
-max- dookie7912 years ago
yes you need insulated wire. go to radioshack and find the magnet wire (enameled wire)

TheBoss20122 years ago
you are going to want to use a battery with the most amperes possible. also, you should use the thinnest magnet wire you can. (if you dont have magnet wire, use wire with very thin insulation.) and make the coil as big as you can.
try amazing1.com's electromagnet its powerful enough to lift a car
thinner is always better
go for a few layers; too many will take away from the conductance of the copper
higher volts = better
I'd go for nine if I were you
but listen, here's the thing
if you really want power for a split second, you might want to try to discharge current from a flash capacitor into the coil
(a flash capacitor is the kind found in the digital cameras)
that will give you a really strong jolt of magnetic tug
comodore (author)  The_Vinninator5 years ago
Hmm, that sounds like something i need....I need a strong magnet flash, but it has to happen like 1-2 times in a second...will it be enough to charge the capacitor? OK, nine turn....finally, some exact data! How thin would you go 32,36 gauge? Thanks The_Vinninator!
sorry, I didn't mean nine turns I meant nine volts but don't just limit yourself to that if you can combine batteries, that would be the best option your best bet would probably be to wire up a few nine volts in parallel what you would do is have more than one capacitor actually, can you tell me what you're using it for? that way, I can give you the best recommendation you want to go thin, but not so thin that it's resisting the current either 32 or 36 should work about the same anything else?
Greetings Vinninator: I am in the process of building an electromagnet and would like your opinion on the materials I am going to use. I am going to use a u-shaped metal from an old lock that is long enough to use instead of a nail. I am also going to use a D battery and the wire looks like a telephone wire and it also appears to be insulated. I've read that insulated wire tends not to get hot as fast as other wires, I don't know if that is true, will see. So, what do you think???. Thanks. AL.
P.S. I saw a video of someone who used an electromagnet to pick and drop objects: How was that done??. Thanks. AL.
comodore (author)  The_Vinninator5 years ago
Well, I posted this question for a lot of reasons, got a big use in lots of my projects... But, right now I want to make an electromagnet inductor...whit a solenoid and a strong electromagnet.... the electromagnet goes into the solenoid and I use a bush button to turn on and off the electromagnet inside the solenoid and induct current....
in that case, I'd just go with what I told you a few nine volt batteries in parallel should work and ya... also make sure whatever you wrap the magnet around is clean and you don't want to have too many layers of wire because that brings the wire AWAY from the core would it be possible to avoid all this and just use rare earth magnets?
Are earth magnets stronger then an electromaget???. Thanks. AL.
comodore (author)  The_Vinninator5 years ago
would it be possible to avoid all this and just use rare earth magnets?
  • well, yes, but I am working on a device and I need an electromagnet...so in this case no, but in other cases yes....
Thanks a lot! You really helped! :D
that's what I'm here for, bro *cyber high-five anything else, just pm me!
comodore (author)  The_Vinninator5 years ago
OK, if i have more questions and I probably will I will PM you or leave a question on your orange board...

Just 1 more question! :D
  • How many volts can I get from electromagnet induction, if I had a small coil whit more turn, thinner wire and a very strong electromagnet that is supplied with 9 V???
Thanks!
how many volts? It sounds like what you are saying is how much inductance (magnetism) can you get... inductance isn't measured in volts, it's measured in gauss I don't know how much gaussometers go for... honestly, almost ANYTHING can affect how much strength you get from the electromagnet don't expect to be able to lift a few pounds, but at the same time, if you make it really well, you might just be able to it's really too hard to say
I'm sorry to interject but inductance is measured in Henries. Gauss is the unit of magnetic flux density.
you're probably right about that sorry but I don't really understand the difference care to explain?
hi Vinninator,

i've a problem with electromagnet, its rise time is 100 milli second while i need something around 100 micro second, i'm using steel nut 16mm dia as core, wire is awg 24, and resistance is around 10 Ohms
could you help me how to reduce the electromagnets rise time.

thanks
Inductance is the property whereby a circuit opposes a change in current. When it experiences a change in current it will produce a 'back EMF' or that will oppose the change. One example of the use of this is a starter coil in a petrol engine (diesel works by compression). A high current from the battery flows through the inductor, when this current is cut off, the inductor generates a high voltage in an effort to maintain the current. This high voltage pulse is allowed to arc over the spark gap and this ignites the petrol. The magnetic flux density is basically the strength of the magnetic field. S you can measure the 'strength' of a magnetic field at a particular point in Gauss (the Tesla is also a commonly used unit). AlexHalford
comodore (author)  The_Vinninator5 years ago
No,sorry, you didn't understand my question... When I put an electromagnet in the coil and start turning it on and off...how many volts do I get from the secondary coil???
O that's what you meant... well, you would get the amount of volts in the power source minus the amount of resistance in the first electromagnet (you can test this with a multimeter) assuming you put it in series if you wire 'em up in parallel, you'll get the same amount of voltage in both (not taking into consideration any other factors)
comodore (author)  The_Vinninator5 years ago
Could you please take a look at my new question, I see you know quite a lot....
http://www.instructables.com/answers/Build_a_Small_Tesla_Coil/
Thanks!
sure thing I used to work with electromagnets all the time in science projects
comodore (author)  The_Vinninator5 years ago
Thanks!
comodore (author)  The_Vinninator5 years ago
OK.... Thanks for your help! Keep in touch! :D
you're very welcome anytime
What about using carbide as a core for an electromagnet? It can withstand very high temperatures and is magnetic due to the cobalt binder used to make it.
Watch out though! When doing this be aware that the coiled wire and the battery will get warm and maybe get very hot!
comodore (author)  jarren.horrocks5 years ago
Hmm, well, how can i prevent that and make it so that it can stay on for hours???
Really, there is almost no way to cool it down if using a high voltage. But without the high voltage, there is no powerful electromagnet (google search 'how to keep an elactromagnet cool').
There is a way to build very powerful electromagnets without useing large amounts of power, without cooling problems. You wrap a soft iron core with hundreds of 20 inch strips of 33 gauge magnet wire. clean the insulation off the ends of all the wires and solder all the ends together so you end up with somthing that looks like a braided cable. this cable will have a very low resistance. You wrap the cable around your soft iron core. so you basicaly have a soft iron core with many turns of this fine wire that are combined into a cable. This electro magnet has very low resistance and a large amount of ampere turns. requires a low amperage. A word of caution this makes a very powerful magnet, so be very careful.
rockplourde when you said "20 inch strips of 33 gauge magnet wire. clean the insulation off the ends of all the wires and solder all the ends together so you end up with somthing that looks like a braided cable". do you just solder each end to the next one like a long cable im not sure what you mean by braided would i braid the strips
The ideal practical electromagnet has a very low resistance. A ferrous core (such as a nail) and more turns will make it more directional, ie focusing strength in one direction at the expence other directions. Thinner wire allows more turns in the same space, but you get a higher resistance and therefore less efficiency. You need to compromise between overall size, number of turns, copper gauge and type of core. The simplest way to drive the electromagnet with a battery is by incorporating a series resistor or using thinner copper wire. A far more efficient way to drive the electromagnet from a battery is via a 'switching' regulator. This can convert the constant voltage of the battery to a constant current (at a very low voltage) at the electromagnet without wasting too much as heat. Using a switching regulator means that the electromagnet can be made to be much closer to the ideal without worring about the battery voltage, and the battery will last much longer. A simple switching regulator will work best using a battery of about 4.5V or more (but lower is possible). The downside is that a switching regulator is not a simple circuit, but it is something to consider if you REALLY do need a small and high strength electromagnet and a long battery life. As a guide, a switching regulator will need a high-current ferrite inductor, a fast power diode, a fast power transistor and a control circuit (usually one integrated circuit plus a few minor components). Sorry I can't supply a circuit diagram. You might find something on the internet.
comodore (author)  jarren.horrocks5 years ago
hmm...that posts a big problem for my project, than again...it will be turned on and off every 0.1 or less seconds for about, again 0.1 seconds.... I don't know what i am going to do...i will get on to some tests and see... Thanks!
legionlabs4 years ago
There is a wonderful technology called an electric double layer capacitor (also known as a pseudocapacitor).

You can buy a 2.3 volt 120 Farad (not a typo) device for around 16$, it is slightly smaller than a 9v battery. You will also need a 2V voltage regulator to charge it.

This will allow you to apply much higher currents. If you need to control it, use a power mosfet. Keep in mind that energy stored in a capacitor is 0.5*(capacity)*(voltage^2). That is 240 joules in this case, be aware that this can output the energy fast enough to heat your electromagnet to red heat and set your pants on fire (if it is in your pocket).

To buy one, go to www.digikey.com and search for "pseudocapacitor".

Good luck Re: Awesome painful disaster.
It sounds to me like you should just buy a tattoo gun and use the EM/ Solenoid off of it. Comes with a plug in power supply, adjustable speed control... everything it sounds like you need. You can also buy just the parts you need, and save some money. Google it.
Kiteman5 years ago
To increase the strength of an electromagnet, do as many of these as possible:

  • Put more turns on the coil (which may need narrower wire to fit more on the core).
  • Put more current through the wire
  • Apply more voltage
  • Use a ferrous core.
How far you take these depends on the space and battery you have available.
comodore (author)  Kiteman5 years ago
Thanks, but here is the thing, as I sad, I need to use the smallest voltage that I can use, in a way it has to be energy efficient... Thanks!
The trick is to find a balance between the four variables.
comodore (author)  Kiteman5 years ago
So, what you are saying that I can actually put too many turns, or to thin wire?
More turns = more wire = greater resistance = less current = weaker magnet.

Thinner wire = greater resistance = ...

But, at the same time, more turns = greater concentration of magnetic field.

Like I said, balance. Kelseymh will know more about this, but it's worth playing with for your own education - try different coil configurations to see what works best.
comodore (author)  Kiteman5 years ago
Yea, I see... Also, there are some comments that say that the wire and the magnet will get very hot very quickly...is there a way to make it so that i can stay on for hours...??? Thanks
Not with a normal AA battery - a coil of wire is effectively a short-circuit, so an electromagnet will kill off a battery in short order.
comodore (author)  Kiteman5 years ago
hmm...who can this be avoided, whit out the battery or....?
Maybe add a resistor?
comodore (author)  Kiteman5 years ago
...yea... Today, I tried to make one but it was very weak...but...I only had two turns whit thick solid telephone wire, on a small piece of metal... I need the electromagnet to make a Faradays device that makes AC current... you know the device, whit a coil and an electromagnet inside and i repeatedly turn on and off the electromagnet and get AC current coming from the coil... I tried that whit a small coil and an electromagnet, but got a very strange result... When i was turning on and off the electromagnet inside I didn't get any AC voltage and as soon as I disconnected one wire from the coil from the multimeter, the current jumped to 2 V AC and started to drop very very slowly, about 0,01 volt per 5 secs....than I connected the wire back to the multimeter and again 0.00 volts! How is that possible???
The meter can be a fooler... it can pick up voltage out of the air. I think my previous comment got eaten, but what I said was that the more turns in the secondary, the higher voltage you'll see from your electromagnet being turned on and off. If you leave the electromagnet on, your secondary will show nothing. It is only when turning it on and off that the secondary voltage will be seen. 2 turns is probably not enough to see anything on the meter.
Seriously, you need to ask kalsyhm.
comodore (author)  Kiteman5 years ago
OK, I will! Thanks!
110100101105 years ago
what makes an electromagnet many times stronger is a closed magnetic circuit you know those U shaped magnets ? they are not super strong. but they hold way stronger a piece of metal that touches both ends at the same time - as in 'short circuiting' the magnetic power if you want your electromagnet to hold a piece of metal strongly while it allready touches it - build it so that the piece of metal shorts the magnetic power if you want it to pull the piece stronger - see if you can make an allmost closed circuit. for example connect the piece of metal to the other side of the electromagnet with a magnetic conductor (thick piece of iron or steel) as for the electro magnet itself - what matters is amount of turns X current. what determines current in dc is the resistance of the wire only. so you want a long coil. the longest one that still does not have too much resistance maybe convert the voltage to ac and give ac to the magnet. i dont know for sure but i think electromagnets work more efficient on ac
comodore (author)  110100101105 years ago
Thanks for your help! I think I am going to wind lot of turns, as many as I can whit a very thin wire... I am going to use 1,5 V battery... I think that will work fine, i hope it will be powerful enough... Thanks!
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