EI Core electromagnet questions

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SUMMARY

This discussion focuses on the design considerations for an EI-core electromagnet, specifically the configuration of the core and material selection. Users debate whether to construct the core from two C-shaped halves or to use a combination of E and I shapes. Iron is recommended for its cost-effectiveness and high permeability for DC applications, while ferrite is discouraged due to its fragility. Key questions include the necessity of laminations and the specifics of the power supply and control mechanisms for the electromagnet.

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  • Understanding of electromagnet design principles
  • Familiarity with core materials like iron and ferrite
  • Knowledge of DC power supply specifications
  • Basic concepts of magnetic field generation and control
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  • Research the effects of core shape on magnetic field efficiency
  • Learn about the properties of iron versus ferrite in electromagnet applications
  • Investigate methods for controlling electromagnet current and voltage
  • Explore the implications of using laminations in DC electromagnets
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Engineers, hobbyists, and students involved in electromagnet design, as well as anyone interested in optimizing the performance of DC electromagnets.

pvonlock
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Hello. I am trying to design an EI-core electromagnet (think two c-shaped cores with their gaps abutting). The coils would go on the top and bottom legs of the E (legs B and C in my sketch). There is a sketchbelow and you can find one here: http://www.everychina.com/m-ei-core?cpc_kw=ei core lamination&cpc_flag=c66082

I had a few questions

1. does anyone foresee any problem with making it in two c-shaped halves (1/2 A+C+1/2 D and its mirror on B) then joining the two?

2. Would it be better to make it as an E and an I and join them? If so, why?

3. I have the chance to make this out of iron or steel, and maybe ferrite. It's being run DC so my thought was iron (relatively cheap, good permeability, and customizable). Does anyone foresee problems with iron?

Thanks to all.

A
++++++++++++
+ ++ +
B + Gap + C
+ ++ +
++++++++++++
D
 
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An electromagnet needs a gap that will close, or somewhere for the magnetic field to get out to attract a nearby object. You know what you want but we are not mind readers and cannot guess the details needed to usefully advise you. Draw a sketch of your core, show where your windings will be placed and where the magnetic field will flow to attract whatever.

Ferrite is not good for electromagnets because it will shatter if hit by some attracted object.
Laminations are only needed for AC transformers or high speed magnets.

How quickly do you need to turn the magnet on, and how long to turn the field off ?
Why are you using laminations when you could use solid iron blocks bolted together ?
What size dimension is your design ?
What power supply will you use to power the magnet. Voltage ? maximum current ?
How will you control the magnet current ?
What is the application of this electromagnet ?
 
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Most likely this can only be answered by an "old timer". I am making measurements on an uA709 op amp (metal can). I would like to calculate the frequency rolloff curves (I can measure them). I assume the compensation is via the miller effect. To do the calculations I would need to know the gain of the transistors and the effective resistance seen at the compensation terminals, not including the values I put there. Anyone know those values?

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