How to build a stonger Electro-Magnet

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SUMMARY

The forum discussion centers on optimizing an electromagnet design to prevent wire melting and improve magnetic field strength. Users recommend using a ferromagnetic core, such as iron or mild steel, and suggest increasing current or wire turns to enhance magnet strength. A variable power supply is preferred over batteries for consistent power delivery. Resistors are essential for managing current and preventing overheating, with specific recommendations for resistor values and configurations provided.

PREREQUISITES
  • Understanding of electromagnet principles and design
  • Knowledge of Ohm's Law for calculating current and resistance
  • Familiarity with ferromagnetic materials and their properties
  • Experience with electrical components like resistors and power supplies
NEXT STEPS
  • Research the properties of ferromagnetic materials for electromagnet cores
  • Learn about variable power supplies and their applications in electromagnet circuits
  • Study resistor configurations in parallel and series to manage power dissipation
  • Explore calculations for electromagnet strength using wire turns and current
USEFUL FOR

This discussion is beneficial for students, hobbyists, and educators involved in physics projects, particularly those focused on electromagnet design and optimization.

  • #31
You would only if the 5 resistors are of the same ohm value.
 
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  • #32
ok i see now.

Thx:smile:
 
  • #33
Let me guess. You did some more math?
 
  • #34
How did you know:-p ? I never put three 50 ohm resistors in series on my electromagnet before because i thought they would all take 21.66 watts of power and overheat.
 
  • #35
Hover:
"DHS Science i have a question for you, how strong are you trying to make your electromagnet? Are you just trying to run some current through a wire to create a simple electromagnet or are you trying to create the strongest electromagnet you can make??"

I am trying to make the stongest that i can with the supplies that i have.

Averagesupernova:
DHS, you haven't told us what gauge wire you are using in your electromagnet. You are using 1 megohm resistors with a 12 volt battery? There is NO WAY a one megohm series resistor can allow enough current through from a 12 volt battery to melt your wire.

Sorry about not saying the size of wire, it is 6 gauge. And the reason that the batter melt thru the wire last year was because i never used a resistor then. I just ran a wire straight off of the battery thru the coil. That is the main reason why i have so many questions. Sorry.

Last night i went out and bought a pack of 2 resistors that allow 100 ohms and 10W. So if hook both of them up parallel in the line then i should be fine? Because if i do then the power will be divided evenly between the two resistors and will still only allow 10W thru in all, correct?
 
  • #36
DHS Science said:
Last night i went out and bought a pack of 2 resistors that allow 100 ohms and 10W. So if hook both of them up parallel in the line then i should be fine? Because if i do then the power will be divided evenly between the two resistors and will still only allow 10W thru in all, correct?
With six gauge wire the resistance of the coil will be close to 0.
Power in resistor is E squared times R.
In this case 12^2 /100 = 1.4 watts.

The resistor does not limit watts.
It only provices resistance.

#6 wire should be able to handle about 30A to 40A without heating up too much.

Current in the coil is E/R.
Or in this case 12/50 = 0.24A

You may want to use smaller resistance value.
For 10W resistors 30 ohms is about as low as you want to go with a 12v source.
This provides a safety factor since the 10W rating is only for ideal conditions.
 
  • #38
If we were to use a power cord from a computer then how much power (amps, volts, watts) would that allow to enter the magnet if we were getting our power straight out of the wall?

Sorry if I am asking stupid questions but I would really like it if we would not burn the school down.
 
  • #39
DHS Science said:
If we were to use a power cord from a computer then how much power (amps, volts, watts) would that allow to enter the magnet if we were getting our power straight out of the wall?

Sorry if I am asking stupid questions but I would really like it if we would not burn the school down.

Are you saying how much power would you get out of the wall if you plugged in a power cord and used that?? That all depends on the rating of voltage from the power cord. It should be listed right on it.
 
  • #40
The power cord does not give an answer directly if just gives (what appears to me at least) a random configuration of numbers and letters.
 
  • #41
Why the heck is this still in this section of the forums? Someone move this to electrical engineering.
 
  • #42
DHS Science said:
The power cord does not give an answer directly if just gives (what appears to me at least) a random configuration of numbers and letters.

It should be right on it somewhere. If you can't find it get a volt meter and measure it that way.
 
  • #43
Averagesupernova said:
Why the heck is this still in this section of the forums? Someone move this to electrical engineering.

You know there is a feature called "Report Post" on the lower left section of a post (exclamation mark). Just report the thread and request that it be moved.
 
  • #44
We decided to use a car battery so it is pushing out 12 volts and the wire that we are using is still getting really hot. In order for the coil to maintain the same strength we hooked a battery charger up to it, which did the job but should we put a breaker (like from a fuse box) in it to help maintain the amount of amps?
 
  • #45
DHS Science said:
We decided to use a car battery so it is pushing out 12 volts and the wire that we are using is still getting really hot. In order for the coil to maintain the same strength we hooked a battery charger up to it, which did the job but should we put a breaker (like from a fuse box) in it to help maintain the amount of amps?

But to use a fuse, you would need to know how much current the wire can handle before it becomes a danger. The amount of amps depend on the wire gauge. There is no use in getting a fuse that's rated for 7 amps when your wire can handle more.
 
  • #46
well we have 6 gauge wire and i was going to put a 15 amp fuse in the circut but i am not sure if that is still to many amps
 
  • #47
There are many tables on the internet that will tell you how many amps your wire can handle. Look it up and then you will be able to choose the appropriate fuse rating.
 
  • #48
There is significantly more to it than just sizing the fuse to the amount of current that the wire will handle. If you wind several hundred turns of #6 onto a large rod and hook it up to a 12 volt battery with a fuse that is sized at the maximum safe current allowed you will most likely blow the fuse right away. The fuse does not 'regulate' the amount of current allowed to flow. It will allow any current to pass up to a given point and then open up preventing the current from flowing. You need to wind enough wire to get enough resistance so that the natural resistance in the wire will not allow more than X current to pass at a given voltage. Naturally this causes problems because to get enough wire wound to get to this resistance we may have a coil with a 5 foot diameter. The link I gave earlier in this thread should explain it well.
-
http://www.solenoidcity.com/electromagnet/E-28-150p1.htm
This link goes to one of their products which shows wire size related to reisistance of the windings related to the duty cycle at various voltages as well as a few other things.
 
  • #49
i went through the discussion...i'm making an electromagnet with a cylindrical iron core(2.5 cm dia, 8 cm height)... i used a 12v 1.3ah battery and it got drained in no time ! 20 seconds i guess... I'm thinking of buying a 12v 10a battery ... is it necessary? i want the electromagnet to work for 30 mins. what resistor should i use ... will adding bridge rectifiers help ??
 
  • #50
Hello fellow hobbyist,
I was wondering if using an actual magnet (cylindrically shaped ) as the core itself in an electromagnet would make a stronger magnet, make no difference, or make it weaker...thanks - I look forward to hearing from you guys...
 
  • #51
This thread is several years old.
 

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