Speedometer Magnet

[ALJ]

My Speedometer magnet is dead. How do I recharge it? The speedometer is the oval shaped SW speedometer. It is disassembled. I may have caused the problem by getting the magnet to close to some tools made of ferrous material.

Do you think placing a strong horseshoe magnet across the poles of the speedometer magnet would recharge it?

I expect someone to suggest sending it to Papa Nick. That may be an alternative, but I would like to do this myself if possible. That is what I enjoy about this hobby.

Any suggestions will be appreciated.

[Mark in MT]

You can charge it up using a strong magnet, be sure to keep the same polarity or it will go dead in short order. I use an electro magnet charger made by Stewart Warner, it has 3 settings, usually use medium. Some times it will overcharge, sometimes I have to use high, just trial and error.

[ALJ]

Originally Posted by Mark in MT

You can charge it up using a strong magnet, be sure to keep the same polarity or it will go dead in short order. I use an electro magnet charger made by Stewart Warner, it has 3 settings, usually use medium. Some times it will overcharge, sometimes I have to use high, just trial and error.

Thanks for the reply. When you say keep the same polarity, does that mean north pole to north pole and south to south? I thought it would be opposite that.

[pooch]

I am wondering how you determine north and south on a round magnet?

[160B]

Correction: Thanks Mark for refreshing my memory!!

The magnet is a horseshoe shape and the sliding window affects the magnetic field in the air gap between the N and S pole of the magnet which allows calibration.


The truncated triangular shaped piece in the attached photos provides the air gap between the N and S poles of the magnet.
otos.

[Mark in MT]

Sponsored Links (Register now to hide all advertisements)

The magnet itself is a horseshoe magnet with the ends pushed together to make a circle. The very early ovals had no wedge shaped piece in them, the hole was open between the ends, and had a temperature compensating brass part on top of the magnet.

[pooch]

edit