Magnetization of Old Analog Meter's Magnetic Yoke: Calibrating & Restoring Lost Magnetic Field

Question

Hello. Strange topic, but I have a thought in my head. There is an old analog meter. It has a magnetic yoke and here is my doubt. When trying to calibrate (let's call it) I don't get a repeatable indication. I will switch the range, change the position of the pointer, then come back and...

Anonymous · Accepted Answer

Why the idea of a fairy tale? Important where will you put an extra magnet? Of course, it cannot be added to the moving part. It should be placed in such a way that its field possibly affects the core of the old magnet and not the winding. The old core will suck in the new magnetic field but only to the extent that the material constant of the old magnet allows, achievable coercivity. It will only be larger in the gap between the magnets and in the very thin gap layer of the old magnet. As the fold turns out to be too strong, you can add a thin spacer, which will regulate the magnetic circuit.
Take into account that an old magnet subjected to a strong neodymium magnet will increase its own magnetization over time. It's like magnetizing a paper clip.

klamocik · Accepted Answer

This is not the fault of the magnet, or; hair; crooked brushes rub against each other or the casing or looseness in the suspension of the body, these are adjusted with a screwdriver.

zdzisiek1979 · Answer

Well, you could add a bite of fresh field, but there is little space in the housing.
But I have now done tests for repeatability of indications and it is not fun.

Giving uA is ok I set the current to have a reference on the scale. I break the circuit and switch on the indications for approx.
By applying voltage, maintaining the reference scale and moving the system, the pointer already travels about 2mm from the reference. For it to come back I have to break the circuit and supply it again. I guess this is because I suspect that the magnet has lost some of the power that affects the coil.

I will think about it.

zdzisiek1979 · Answer

I don't know.

This is what the system looks like.

I do not notice slack.
The magnet is behind the silver cover. Between two pole pieces.

Now the question is, if I would add neodymium pills, would it not spoil the magnetic field. They are in the store like what.

I assume that after the movements of the system, the magnetic forces should bring the coil to the correct position as it occurs after "voltage reset".

Added after 2 [hours] 53 [minutes]:

However, the ticking of the magnet is a broken idea. I put neodymium and ... the system to be thrown out. You can't play like this because it will only get worse.

Well, I stated experimentally

and the application one "Do not magnetize"

Best regards and thanks for the feedback.

Magnetization of Old Analog Meter's Magnetic Yoke: Calibrating & Restoring Lost Magnetic Field

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