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Picture of Strong Electromagnet From An Old Transformer
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This is a very strong electromagnet made out of an old transformer.
The materials used are recycled from transformers and motors.
This magnet can lift over 30lbs (14kg)

 
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Step 1: Parts & Tools

Picture of Parts & Tools
02_transformer.JPG
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Parts:
1 Transformer
Enough magnet wire to fill the core.

Tools:
Box Knife
Pliers
Slotted Screwdriver
Small Hammer

Step 2: Disassemble The Core

Picture of Disassemble The Core
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08_core_disassembly_1.JPG
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The transformer core is made of layers of "E" shaped & "I" shaped pieces which are held together with varnish.
To separate the layers use a box knife to break apart the first layer, then beat the piece out with a hammer and screwdriver. Once it breaks free it can be pulled out with the pliers.
Once you get the first couple of layers out, put the transformer on a hard surface and hit all sides of the core with the hammer to help break the varnish loose. Then you should be able to get the rest of the pieces out with the knife easily.

Step 3: Wind The Coil

Picture of Wind The Coil
I wound this coil by hand so I didn't get any pictures in the process.
I used wire that I collected from other transformers and motors.
So I ended up twisting together about 15 strands with a drill to make about 50ft (15m) of 22awg wire.

The coil form has a divider between the coils that needs to be cut out in order to wind one big coil.

This coil has 5 layers of wire in it.
The layers must all be wound in the same direction and should be wound as neatly as possible .

This coil will run at 5 volts. For a higher voltage use more turns of a thinner wire.

When using DC to run the magnet, you can estimate the current using a wire resistance chart & ohms law.
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bhry5 months ago

Hello , Mr rocketman221 you done a good Job thanks for share information
I need a help if you would please help me in this
I am working at an electric magnatic for water the pipe diameter is 50 mm and another pipe 65 mm
the volt I use 24 V " transformer from 220 v to 24 v and its AC Voltage "
the pipe is plastic the water well pass throw
and the magnatic well run for 6 hours daily
I need to know how much wire long and diameter and how much layer I need and many layer
and how many turns for layer
realy I Am THANKFUl for your Answer and Information
ANd its my first magnatic project
with thankful

jbrown146 bhry23 days ago
This won't work because AC can't generate a magnetic field.
rocketman221 (author)  bhry5 months ago
This probably won't work very well for what you are doing. It sounds like you are trying to trap metal particles flowing through a pipe. These magnets are great for lifting large pieces of metal, but not very good for small pieces.
I haven't been able to make any that will run for long periods of time and still perform well.
lam2 months ago

Hi rocketman221

Please could you help me to know:
My old solenoid coil has 100 meters of 28 gauge (0.32 mm) . Now I want to build an other but I have only 34 gauge magnet wire (0.16mm) . So Please could you help me to know:
Can I use 2X 100m of 34 gauge magnet wire and 2 wire must twisting together or not need to do(twisting) that ? Thank you so much

jbrown146 lam23 days ago
If you were to do that you would need to twist it. I wouldn't worry about the gauge if your making another one. 34 gauge should work just fine.
rocketman221 (author)  lam2 months ago

That would work, but you need 4 pieces of 34awg wire to replace one piece of 28awg. The wire should be twisted, that will be fun with such a long piece of wire.

dmalamas1 month ago

Hi, could you tell me if this electromagnet works with AC (50 - 100 Hz) input?

Nope, only DC. Cell phone chargers can do the trick. I'm not responsible for you hurting yourself.
cjhynum4 months ago
Could i hook the magnet up to a 12v plug in a vehicle i got the transformer out of a microwave
rocketman221 (author)  cjhynum4 months ago

As long as you wound the magnet suitably for 12v you can. The 12V socket will typically have a fuse around 10-15A so your magnet will have to use less current than that. Keep in mind the socket may supply up to 14V.

Let me know how well the magnet works with a MOT. I have wanted to make one, but never gotten around to it. You could probably lift over 100kg with a magnet that size.

I seen a guy do it on youtube and tried it i wanted to pick metal up out of a field with it but it wasnt strong enough do u have any ideas im not thinking of
AmakW4 months ago

hello @rocketman221.. It is possible to use this electromagnet in the water? If can? How can I make it waterproof?

rocketman221 (author)  AmakW4 months ago

You could dip the whole magnet in varnish a couple of times to seal it.

m.amir.4564 months ago

Hello @rocketman221 i want to make an electromagnet that can move a 10kg object in To and Fro... how can i make it... which wire, its length and no of turns and how many volts (dc)....

rocketman221 (author)  m.amir.4564 months ago

The magnet shown in this instructable will work for what you need. It runs from 5V DC. As long as the object you have has iron or steel that's flat and over 10mm thick, it will lift it.

The magnet has 50 feet of 22awg wire on its core and about 125 turns.

reidintransit6 months ago

what about adding a resistor in series with the coil for cases where the source voltage is too high or coils are too small?

rocketman221 (author)  reidintransit6 months ago

You could, but you will need a high wattage resistor and it will get hot.

avwerosuo1 year ago
Hello rocketman, it's a nice job you are doing keep it up! I am not a professional in this field so I'll need your help. I've a neodymium magnet of 4''diameter x 1.5''long and i want to make an electromagnet of if possible equal force for repelling purpose. I want use a larger core of 3''diameter x3'' long and the electromagnet will operate continuously. Please kindly guide me on the wire size, the number of turns and length of wire that will not generate heat and also operate at low current. Please i need a very strong electromagnet with equal force as the neodymium magnet. I'll be very grateful if you or anyone can give me any useful advice. THANKS!
rocketman221 (author)  avwerosuo1 year ago
Unfortunately you won't be able to make an electromagnet capable of repelling that super magnet using a transformer core. If you were to use an iron core, the neodymium magnet would just stick to it and be very difficult to remove.
You could try using an air core electromagnet, that would be able to attract and repel the neodymium magnet, but won't be nearly as strong as the neodymium magnet.
Be careful with those super magnets, they will crush anything that comes between them and a piece of iron or another magnet.
Thanks for your reply!
But yes i actually wants it to stick together when the electromagnet is switched off and when the electromagnet is connected (switch On), the North pole of the electromagnet and the North pole of the Neodymium magnet will cause them to repel from each other, and when switch off again they stick together.
I don't know if am correct, but i want to know if this is possible.
Thanks for your reply!
barry921 year ago
if DC power supply is used on E-shaped ferrite core electromagnet, will the performance of the electromagnet the same as the one usign AC power supply?
How to differentiate the poles of the transformer, as i want to repel another identical transformer?
Do the armatures of the E-shaped electromagnet exert forces on the other identical one when current is supplied?
rocketman221 (author)  barry921 year ago
The magnets are much stronger on DC. On AC the magnet's polarity is constantly changing and they will vibrate strongly when brought near metal. They will draw less current on AC and the current will decrease when stuck to a piece of metal.
The inner part of the E core is one pole and the outer parts are the other pole.
Two magnets will repel each other when the polarity is different, but they don't like to stay centered on each other. The inner core will stick to the outer core on the other magnet unless something prevents them from moving side to side.
sdhavle1 year ago
which wire did you use?
rocketman221 (author)  sdhavle1 year ago
I have used 22awg wire on my 5v magnets and 28awg wire on my 12v magnets.
Hello rocketman, I have few questions in my mind.
I am working on 12V magnet and using the 'E' shaped core having dimensions (40x26x17) mm. So can you please suggest me the diameter(or gauge no.) and the length of the copper insulated wire needed.
rocketman221 (author)  ankit pundir1 year ago
I would suggest using 28 awg (0.32mm diameter) wire.
I have an open office spreadsheet that will estimate the amount of wire you can fit on a core. Put the measurements in the yellow fields and it will tell you the aproximate length and number of turns that will fit.
The magnet will probably use about an amp at 12v dc depending on the length of the wire.
barry921 year ago
Hi rocketman221, I'm having a problem in building a DC electromagnet for my DIY project, using 22.2v lipo battery.
I have a couple of questions to ask you.
-ferrite rod or ferrite core makes perfect electromagnet?
-When I connect my electromagnet to my DC power supply, it heats up quickly, is this a good or a bad sign?
-it is advisable to use 19 swg or 27 swg enamel copper wire ?
-From the previous comments, 'when constructing a DC electromagnet we should consider the the resistance rather than the no. of turns', what does this statement mean?
rocketman221 (author)  barry921 year ago
If it is heating up too quickly then it's using too much power. How many amps is it pulling at 22.2v?
You can increase the resistance by using thinner wire or using more turns.
How big is the core you are using? The size cores that I used for mine work well at around 10 to 15 watts.
For it to use 15 watts at 22.2v, the coil would need to be about 32 ohms.
I would recommend the 27 gauge wire unless you are using a large core.
I haven't tried using a ferrite core, so I don't know how well they will work.

With a DC electormagnet the resistance of the coil determines how much current will flow. With AC the inductance of the coil will also limit the current used.
Well thx for your reply, I appreciate it.
The resistance across the wire is about 1 ohm, o the current flowing through the coil is about 20+ amperes. I use 10 ferrite rods each with a diameter of 1 cm and length of 16 cm to to build the core of the solenoid. Does a higher watt imply a stronger electromagnet or vice versa?
rocketman221 (author)  barry921 year ago
20 amps is way too much power, that's nearly 500 watts. The wire insulation will burn up pretty fast. That magnet would work fine up to 5 or 6 volts, but not at 22v. You need a lot more turns
Higher wattage will make the magnet stronger to a point anyways. The core makes a big difference too. An iron core in a "E" shape or "U" shape usually works best.
barry921 year ago
Well thx for your reply, I appreciate it.
The resistance across the wire is about 1 ohm, o the current flowing through the coil is about 20+ amperes. I use 10 ferrite rods each with a diameter of 1 cm and length of 16 cm to to build the core of the solenoid. Does a higher watt imply a stronger electromagnet or vice versa?
Machine2 years ago
Very nice, very impressive weight that it can lift and simple construction too. Thanks for showing us.
krrran0002 years ago
i am looking for such type of powerful electromagnet . finally i got it. i will try for it..
thank you
aloving953 years ago
Immagine if you did this with a MOT (microvave oven transformer)
rocketman221 (author)  aloving953 years ago
I was thinking about that, but I have never taken one apart. I don't know if it would come apart very easily.
The small electromagnets are hard enough to pull off of something. I would like to seen what a mot would do.
I have found that microwave ovens are a very good source for copper wire, the main problem is the varnish that that is used on the coils when they are made is very tough leaving sharp fragments stuck to the copper wire as it is unwound, which can act like a saw if pulled over unprotected hands.
Never the less around 1/2 a kilo of copper magnet wire from an old microwave oven destined for the garbage bin can't be all that bad, and if any one knows of a way to soften the varnish that is used to hold the coils together 'with out damaging the wire's insulation' ........
rocketman221 (author)  my project box2 years ago
Wrap the wire around a metal rod or a screwdriver and pull it tight over it. It will straighten the wire and break extra bits of varnish loose.
WARNING
please don't try this with a MOT
I alredy have and it killed preaty much evrything electronic around it when I hooked it up to my electric fence power supply.(10 000 volts)
It also sucked the ring I was waring to it and I started getting zapped by the current.ouch.
I Found a MOT that was messed up and the lamanations were bolted together. ill try and post a pic when i finish winding the giant bobin
Mazdak672 years ago
Can anybody help me how can I build such above powerful electromagnets with the same size of transformers and connect 8 of them in parallel to a 4.5 amp 24 Volt DC power supply?
The temperatures should not goes above 80C.

Please tell me the wire turns and diameter in mm.

Thanks

Mazdak
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