Remagnetise Compasses?

My analog car compass (old fashioned type with the magnetic needle) quit being accurate even when I tried recalibrating. I tried an experiment. I pointed one of those small but powerful telescoping magnets at the needle several times and the compass now seems to work normal. Is this something that must be done from time to time? Do magnetic abberations in areas of electrical inrterference cause compasses to become demagnetised?

What makes you think a compass needle is magnetized?

Yes, it is possible that you had to remagnetize the compass. Anything can become undone or just weak. What you did was just what was done when the compass was made. It’s great when science works.

It is likely the compass had some kind of interference. It didn’t lose its magnetism. I have tried several old fashioned types of compasses in both a semi and in a car, and it is difficult to trust them. Finding a place to put them where they don’t receive any interference is difficult.

Sorry, oldschool, I forgot to mention what type of compass I was talking about. I used the term “needle” wrongly. Actually, this compass doesn’t use a needle, but is the type with the dome with the N/E/S/W letters spaced around it with increments in between. So I’m thinking that one part of that dome would need to be magnetised with the polarity opposite of that of magnetic north to cause “N” to line up with the pointer which is stationary. But wouldn’t an actual needle type compass need to have one end of it’s needle magnetised the same way so only it would be attracted to magnetic north and always point to “N” on the compass dial? Or, are the needle and the dome each nonferrous metals with a bit of nonmagnetised iron at the point that indicates magnetic north? Maybe my dome somehow got affected by long term exposure to electrical interference, and my magnet corrected (degausssed?) it? I guess I don’t really know what happened to my compass to make it unreliable, but my magnet experiment seems to have corrected it.

Whitey, this reply may appear twice, but I don't think I submitted it right the first time, I don't see it in the thread. 
Your reply makes sense, but the compass was in the same location on my dash, and the car was driven in the same areas in the parking lot when I was  recalibrating the compass both before and after I did my magnet experiment, so there was no interference before the experiment that wasn't also there after the experiment. And I noticed the compass was inaccurate for quite a while before my experiment.

It does stand to reason that the compass needle it self would have to be magnetized and polarity noted. I was thinking of the old trick of a sewing needle in a cork the the cork in water the needle is not magnetized but it will point to the poles you just won’t know what end is pointing to what pole (unless you know generally which way is north or south) sounds right?

I guess so. And it would seem that a magnetised needle would be more useful!

Gudenteit, Magnetic Compasses Were OK When The World Was 2-Dimensional.

We’ve kind of gotten away from them now that the world is 3-D. Satellites (They’re up there. You just can’t see them!) in geosynchronous orbit above the earth have provided this new third dimension. That compass has exceeded its useful life expectancy, trust me. “Its ship has sailed.”

I don’t know what sort of financial footing you’re on, but for $100 - $300 you can get the most amazing “compass” you have yet to see. They are sometimes called GPS (Global Position System) units.

These little guys can sit in front of you in your car and guide you the entire way from East Hay Stack to Disney Land, if that’s where you’re going. You see a map that adjusts to your location. You don’t even have to look at the map because they talk to you politely, too! They even say things like, “Turn right in .4 miles on Any Town Road.” They know the time, They know how many miles are left in your journey, they know your speed, compass direction, they know when you will get to your destination, longitude and lattitude of your current position, and even know how to get you home from anywhere without a map. They remember where you live! They tell you every turn along the way and can even find you a rest area, a McDonalds, and even a compass museum.

I recommend one with “spoken street names” rather than just “turn-by-turn” directions. The leading brands are Garmin, Tom-Tom, and Magellan. I got mine at Wal-Mart on “Black Friday” for $147 and it has “spoken street names”.

Consumer Reports magazine has good advice on features and buying suggestions.

You will be absolutely blown away!

Magnets CAN loose their magnetism. It depends on what it was made of.

Magnets used in speakers come in two flavors…Alnico or Ferrite. The older Alnico needs to be re-magnetized over time. Where as the newer Ferrite magnets don’t. So if the compass needle was made of the older Alnico then it could have lost it’s magnetism.

Placing the magnet next to the compass may have degaussed the compass. Degaussing is the removal of a magnetic field from a component by using a magnet. Your computer monitor automatically degausses itself each time it’s turned off to remove any magnetic fields that could effect the monitors display.


My two cents worth. A magnet in a compass that could be recharged externally would lose its magnetic dipole easily, i.e. the magnet is soft. Any degausing field i.e. an oscillating magnetic field of a transformer or the like, nearby could easily degaus a soft magnet. This occurs in color CRT when the degausing coils are activated by line frequency.

Thanks for sharing your experience.

A compass needle MUST be magnetized to work…Sounds more like the BEARINGS, the parts that support the “card” are stuck or worn in the OP’s compass…Compasses seldom work correctly in a automobile because of all the steel sheet metal and the powerful magnets typically found in radio speakers…

Actually, GPS satellites are not geosynchronous, they are considered to be in a semisynchronous orbit since they do not return to the same spot at the same time. They lag position by about 2 minutes each orbit or 4 minutes each day.

I Stand Corrected. I Should Have Stated Semisynchronous Rather Than Geosynchronous. Sorry For Any Confusion That I May Have Caused.