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Relay electromagnet magnetization. Types of relays for maximum magnetic dynamic range

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Advanced Member level 6
Jan 5, 2008
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I would like to vary the magnetic permeability of a cored coil using an electromagnet, taken out from a relay.

I want to be able to apply from very small magnetization to the coil, up to quite large, so I need high magnetization dynamic range (if such term exist).

For that purpose:

1. What types of relays should I best choose?
2. What voltages of relay coils should I choose?
3. I guess, the more turns in the relay coil the best? (if so, greated coil voltages have more turns?)

For example I have seen this relay the "very sensitive type", which operates even at 2v. Will in general low voltage relays have more turns, so they can produce more magnetization force?

As I said, my interest is not on the pull-in voltage but using the relay coil as an electromagnet.
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One starts with a known datasheet with coercivity and Bsat then uses common calculators for magnetizing the core.

You can choose wire guage based on current, area, diameter, size constraints and number of turns from the calculations.

I want to be able to apply from very small magnetization to the coil, up to quite large

Relays do not need much power through the coil. It only needs to be sufficient to pull in the mechanism.

Instead of a small relay, I believe a large relay is more likely to provide your maximum energy.

I think your best solution is the old-fashioned experimenter's electromagnet. Wind many turns of enameled wire around a soft iron nail. Do not use vinyl or rubber coated wire.

I once made a larger version of the same thing, in an attempt to strengthen a declining magnet in an old D'Arsonval movement. I started with a metal rod from a piece of furniture. I bent it into a 'U' shape. I wound a few feet of magnet wire around it. I connected it to a 12V car battery. It drew several Amperes. It became hot within a few seconds. It was almost strong enough to do the job.

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