Compass in a car?

G

Grapevine

Joined
Mar 5, 2002
Messages
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Sorry if this has been discussed before. My search function keeps getting error messages.

I've twice bought one of those compasses that you stick on the dashboard or windsheild of the car, and they never work. I'll test them with another compass outside the car and they seem to be fine, but inside all the compasses I have are kind of iffy. When the car is running forget about it, they all end up pointing in different directions depending on where they are inside the car, and the needle stays there regardless of the direction you're heading in unless you move the compass to another part of the car in which the needle will then point differently.

I'm assuming that the car's engine is creating a magnetic field? And when not running the metal structure of the car makes compass readings not reliable?

If so, is there a method of telling which direction you're heading when you're driving? And why the bloody poop do they sell those car compasses if they're not going to work inside a car?
 
Grapevine said:
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I'm assuming that the car's engine is creating a magnetic field? And when not running the metal structure of the car makes compass readings not reliable?
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Correct. There are a number of things that make taking a magnetic reading inside a car difficult.

If so, is there a method of telling which direction you're heading when you're driving?
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Once adjusted, electronic flux-gate compasses work pretty well. As in life in general, you get what you pay for.

And why the bloody poop do they sell those car compasses if they're not going to work inside a car?
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I think you said it best:

I've twice bought one of those compasses that you stick on the dashboard or windsheild of the car
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I have a compass built into my rear view mirror and it works fine. The drivers manuel for my car says that if the compass has to be calibrated you should drive the vehicle in three complete circles at less than 5 MPH..
 
The factory compass in the Lincoln works just fine. It's an electronic compass that compensates for the metal and magnetic fields in the car. It calibrates the same way as Larry B's, and you have to tell it which zone you're in.

You should be able to buy something similar to stick on the dash.

-Bob
 
The rearview mirror compasses are flux gate electronic. The real reason they're mounted in the mirror like that is that it gets them away from both the engine and the dashboard electronics.
 
severtecher said:
It's called GPS fellas. Only way to go.
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Until you're standing still. GPS is great, but a GPS receiver can not get your direction until you've moved several hundred feet. GPS receivers aren't really compasses. And compasses can't tell you your location, just your direction. Both have their purpose.
 
Grapevine said:
My search function keeps getting error messages.
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That's because you're not using the right keywords. ;)

Search engine FAQ

Not that there have been a lot threads on this particular subject, but you should not get any error messages if you use it right.
 
Grapevine said he wants it for a car so I assume he will be moving. Most GPS units i have handled will show a change in about 10 meters. That's less than a second at 30 mph. I'd say much more useful than a mere compass.
 
Some handheld GPS models have an electonic compass feature that does not require you to be moving. But with my Garmin you have to hold the unit level - not too helpful if dash-mounted. I believe some of the Magellan units don't have to be held flat in order for the compass to function.

-Bob
 
Same problem with the self adhesive compasses that you put in the vehicle, until I did find the perfect truck with a accurate digital compass. The places you can take your vehicle to get cleaned and washed...wonder if they have anything that is attachable through the cigarette lighter?
 
This reminds me of a story.

I was riding my bike to work, and at a stoplight, the person in the car next to me where a certain road was. I said "West". He asks me what direction West was.

Now, this was late afternoon, and we were facing into the setting sun. I looked at the sun, looked at him, looked back at the sun, then finally looked at him again, and pointed the direction we were already going.

As he was driving away, I noticed he had CA plates.

Now, I perfectly understand someone being unable to find their way around an unfamiliar town, but unless I'm mistaken, even in California, the sun sets in the West.:rolleyes:
 
I bought one of the little digital compasses that mount on your dash, and it seems to work fine(you have to calibrate it, by driving in a circle in a parking lot first). One thing that annoys the heck outta me; it has no light on it that I can find, so the thing is worthless when driving at night. :confused:
 
Danbo reminded me of the other useless thing about the ones I bought. At night you couldn't see them. Well at least then you don't know what direction you're going in instead of thinking you're heading west while you're actually heading south or who knows where.

Oh, and they never stick on the dash very well. Early on the first drive when I tried one it fell off and rolled somewhere in the car. Took me a long time after parking the car to find it because instead of rolling on the floor somewhere it had bounced into the map compartment of the passenger side door.

And all this before I ffound out they're useless!
 
At night you couldn't see them.
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That's funny. Nighttime is the only time I need a compass. :) If the sun's out, I can generally see landmarks and tell direction.
 
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