Building a Wet Compass
Total cost to build the compass was around $80USD
- Opencockpits stepper card
- A small stepper motor
- A real wet compass
- Small gears from hobbie shop ( i used Traxxas 2053)
- 1/16" thin small rod
- a small piece of plexy glass
- 1 Optical Sensor (HOA2001-001)
I used the opencockpits stepper motor cards so that takes care of all the electronics.
As far as the mechanical part basically all the mechanism sits outside the compass above the roof of my sim. I used 3 layers of plexi glass being held together with spacers. I have a small gear attached to stepper motor and a bigger gear with a rod attached going all the way down to the wet compass (or to your gauge needle). The picture should explan it better. On the base part, I made a simple needle out of thin plastic to trigger the optic sensor (not visible on the picture), this is required with the opencockpit cards. When the rod spins, it spins the needle that trigges the sensor.
The only hard part is aligning the gears so they move smoothly, but it just basic meassurements and drilling the right holes.
The stepper moto is controled by opencockpit's SIOC software.
Here is a pic of the mechanism, a simple stepper motor with a few gears from rc cars I got at the hobby shop.