120v coil. need only 3 amps? How do i do that?

Discussion in 'General Electronics Chat' started by ElectromagnetNewbee, Oct 14, 2014.

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  1. ElectromagnetNewbee

    Thread Starter Member

    Jul 13, 2014
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    I just rolled a 120Volt Coil. I am using it as an electromagnet. 24Gage wire.

    I want 3 amps ONLY.

    what do i use to control the ampers? do i just use a couple resistors or what?
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I would investigate the or what end more myself like the concept of Ampere turns and wire length VS its resistance.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Was it wound for DC or AC?
    Makes alot of difference!
    DC? limited by the resistance of the wire.
    What is the application?
    Max.
     
  4. wmodavis

    Well-Known Member

    Oct 23, 2010
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    Use Ohms law If you know the voltage and current X=V/I
     
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  5. ElectromagnetNewbee

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    Jul 13, 2014
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    is Ohms law all that needs to be addressed for AC current? I just want to make sure my 20 amp breaker does not 'break'. So if the coil is designed for 120 volts and 3 amps, then hooking it up to the ac wall outlet it will only push 3 amps? is this correct? for future reference, are amps allows governed by resistance? so i can use resistance to get my required amps? i just need to confirm.
     
  6. ElectromagnetNewbee

    Thread Starter Member

    Jul 13, 2014
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    this i designed for 120v and 3 amps using ohms law. if i hook it up to the wall will it only draw the 3 amps? or will it draw more and cause my 20 amp breaker to go off?
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    No, the resistance of a AC coil is generally very low, it is the Inductive reactance that limits the current, also as I mentioned, a method of retaining the attracted part will usually have to be designed in as it will either buzz like crazy or drop the attracted part.
    The current is also much higher until the attracted armature or object is on the pole piece.
    What is the purpose of the electro magnet?
    Max.
     
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  8. tcmtech

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  9. MaxHeadRoom

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    You still have to confirm if you intend using purely AC or use a rectifier for a DC version?
    If AC the DC resistance of the Coil does not come into it, in fact it is a detriment.
    It will also have a high inrush current.
    Max.
     
  10. ElectromagnetNewbee

    Thread Starter Member

    Jul 13, 2014
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    i want to use AC current from the wall. 120volt. i built the circuit using ohms law. this should be the same for both DC and AC correct? ohms law works with both correct?
     
  11. MaxHeadRoom

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    No , read post #7 and look up inductive reactance.
    An AC electromagnet has very low resistance, the current is limited by the value of the inductance on 50/60hz, and is Inductive reactance in Ohms.
    If you calculate the resistance as for DC, when you come to use it on AC the current and magnetic effect will be a lot lower
    Max.
     
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  12. ElectromagnetNewbee

    Thread Starter Member

    Jul 13, 2014
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    so i just plugged in my newly rolled electromagnet coil into 120v AC wall. wow! way different than DC!

    using DC I get a 'north' and a 'south' pole magnetic field. using AC I do not. will using a rectifier give me both north and south pole fields? how do i get a the north and south pole back like when using DC?
     
  13. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    This will end badly...
     
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  14. #12

    Expert

    Nov 30, 2010
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    Please place your experiments on a long power cord so they might not harm you when they explode.
     
  15. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Skip that suggestion and put a video of your experiments on YouTube where we all can watch! :D
     
  16. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Wow, Who would have thought?? :rolleyes:
    Max.
     
  17. ElectricMagician

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    Jul 26, 2012
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    Get an LCR meter and measure the inductance and the resistance of your coil.
    The average amperage will be [85/(Resistance + 60 * 2pi * inductance)]

    However, I suggest not messing with the mains power and trying your experiments on lower voltages.
     
  18. wayneh

    Expert

    Sep 9, 2010
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    Did you at least hesitate before you did that? That hair raising on the back of your neck is telling you something. If you aren't at least a little afraid, that tells US something.
     
  19. bertus

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    Hello,

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