# 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

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May 7, 2013. 1:25 PMakornblatt says:
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.
May 7, 2013. 1:28 PMakornblatt says:
Also I kept all the magnetic wiring to 22 gauge.
Aug 13, 2011. 5:27 AMyaly says:
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.
Feb 7, 2013. 9:08 PMjwang20 says:
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?
Feb 5, 2012. 8:30 PMPyroTrician95 says:
do u need the wire to be insulated or does it matter?
Jun 16, 2012. 10:58 AMtesla man says:
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.
Jul 31, 2012. 6:38 PMPyroTrician95 says:
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
Jul 31, 2012. 7:15 PMtesla man says:
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.
Nov 5, 2012. 7:25 PMPyroTrician95 says:
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
Mar 17, 2013. 3:59 PMrsteadman1 says:
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...
Feb 17, 2009. 6:48 PMNachoMahma says:
> 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.
Mar 25, 2011. 8:47 PMCivbert says:

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

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.

Dec 12, 2012. 1:37 AMnddarwai says:
thanks bro, it proved needy
Sep 2, 2012. 5:07 PMmb inventor says:
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
Jun 23, 2012. 3:10 AMhussainsk says:
i was prepared to electromagnet 9v battery how much turns required 24 gage wire
May 26, 2012. 2:11 PMthecrazymagnetman says:
I think coil amount does matter
Jan 24, 2012. 10:29 AMdookie791 says:
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.
Mar 1, 2012. 10:39 AM-max- says:
yes you need insulated wire. go to radioshack and find the magnet wire (enameled wire)

Dec 6, 2011. 4:05 PMTheBoss2012 says:
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.
Aug 19, 2011. 6:46 PMIwantbigboom says:
try amazing1.com's electromagnet its powerful enough to lift a car
Feb 19, 2009. 10:15 PMThe_Vinninator says:
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
Feb 20, 2009. 7:26 AMThe_Vinninator says:
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?
Jul 12, 2011. 11:56 AMalsports2000 says:
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.
Feb 20, 2009. 9:11 AMThe_Vinninator says:
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?
Jul 7, 2011. 10:03 PMalsports2000 says:
Are earth magnets stronger then an electromaget???. Thanks. AL.
Feb 20, 2009. 11:06 AMThe_Vinninator says:
that's what I'm here for, bro *cyber high-five anything else, just pm me!
Feb 20, 2009. 8:51 PMThe_Vinninator says:
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
Mar 22, 2009. 12:18 PMalexhalford says:
I'm sorry to interject but inductance is measured in Henries. Gauss is the unit of magnetic flux density.
Mar 22, 2009. 2:00 PMThe_Vinninator says:
you're probably right about that sorry but I don't really understand the difference care to explain?
Feb 19, 2010. 3:22 AMalpha55 says:
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
Mar 22, 2009. 2:31 PMalexhalford says:
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
Feb 21, 2009. 10:17 AMThe_Vinninator says:
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)
Feb 21, 2009. 2:54 PMThe_Vinninator says:
sure thing I used to work with electromagnets all the time in science projects
Feb 21, 2009. 2:54 PMThe_Vinninator says:
you're very welcome anytime
Apr 19, 2011. 9:51 PMHarbringer.III says:
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.
Feb 18, 2009. 7:21 AMjarren.horrocks says:
Watch out though! When doing this be aware that the coiled wire and the battery will get warm and maybe get very hot!
Feb 18, 2009. 12:54 PMjarren.horrocks says:
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').
Jun 29, 2009. 6:48 PMrockplourde says:
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.
Aug 31, 2010. 1:50 PMgilliganking says:
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
Apr 9, 2009. 3:48 PMpw2009 says:
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.
Mar 17, 2010. 8:39 PMlegionlabs says:
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.
Apr 26, 2009. 12:21 PMSpringfield1911 says:
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.
Feb 17, 2009. 2:52 PMKiteman says:
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.
Feb 18, 2009. 1:50 AMKiteman says:
The trick is to find a balance between the four variables.
Feb 18, 2009. 9:25 AMKiteman says:
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.
Feb 18, 2009. 11:15 AMKiteman says:
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.
Feb 18, 2009. 3:21 PMKiteman says: