RitchieSport Compass, black :: Education by Design Store

Customer Reviews

Ritchie Sport Compass

2007-02-15
Instructions for the compass for calibration are easy--align the car in E, N, W, S directions and make adjustments via the two magnetic compensators on the side of the compass. Being a Mechanical Engineer, I was not satisfied with this method, as you rely on a "known" road being truly aligned with a particular direction. So, I purchased a Suunto MC-2DIN orienteering compass to calibrate the Ritchie Sport Compass. When adjusting the settings on the Ritchie compass, the car must be running with as many normally running accessories as possible--including headlights, radio, fan, etc. These accessories affect the electromagnetic field surrounding the compass, which I mounted on my dash with some Velcro tape. I turned everything on, exited the vehicle with my Suunto compass to determine the "true" alignment of the car. I stepped away by about 5-feet behind the car to get away from the car's magnetic field. I would align the car based on the Suunto direction, and then adjust the Ritchie compass to indicate the correct direction.

This worked well for N, E, and S. However, the West direction is too senstive in this design. As I adjusted the Ritchie compass to indicate West, when indeed the car was facing West, the compass would rapidly swivel to indicate either NW or SW. Oddly, the other directions (including East) worked fine and were confirmed by the Suunto orienteering compass and by driving on roads that normally run N, S, and E.

Depressing the brake pedal causes my compass to turn by about 30 degrees due to the change in the magnetic field, which I didn't account for in the calibration. You wouldn't want to anyway, since the brake is mostly not being used when driving. When the brake is released, the compass swivels back to the correct direction of travel.

To wire the compass, I purchased a 12V (DC) adapter from Radio Shack that inserts into the cigarette lighter. I cut the plug off the adapter and spliced it to the two wires from the compass. If you want, you can run wire to the car's electrical box and hide the wire under the dash, but that will take more time and effort. The green LED is just barely adequate for night-time viewing. In my car, the cigarette lighter is disabled when the ignition is off, so the LED light turns off and on when the car is likewise off and on.

This compass has some quirks. The sensitivity of the West direction and applying the brakes are nuisances, but tolerable in my opinion. Putting a compass in a car is not as easy as it sounds if you want true direction. Normal driving bumps, turns, stops, the oversensitivity to West and applying the brakes renders the small graduations meaningless. There is too much variation to rely on the degree tick marks. This compass is useful for determining general directions, such as N, NE, etc. But not to 5 degrees.

Compass

2007-01-09
This compass turned out to be to small for my needs, I do need to return it.