First of all I'm new here so greetings.
Secondly, I've been running over a vintage Aero gauge that I'd like to control with Arduino thing is I have no real data on this particular gauge with exception that it's 24 volt. In speaking with a pilot friend he's telling me that even though the gauge is 24 volt that it should respond to much lower voltages as well.
When I received the gauge I didn't even have data on the pin-out so what I did was remove the cover trace the wiring and then put .5 volts on each of the 3 pins that were not associated with GND. Even after mapping out the voltage I still sit here confused when figuring out where to start on this one. I'm attaching a picture of the mapping that I made. Also, while I hate to assume things it would appear based on how one side maps out that I may have a bad solder OR it's just by design. I'll try my best to not confuse things with this picture.
So the pin-out is A-D and from visual inspection it would appear that D is ground.
Putting power to A gives me a readout on each side as expected based on the wiring layout.
Putting power to B gives me power on both sides as does C. Basically B and C map out exactly the same even when power it applied independently to each.
The return wire marked with 'no voltage' has no voltage on it at any time when power is applied to A-C. It's hard to tell due to age if this is by nature of if I have a faulty solder. The return wire is unsheathed at the connection point and is extremely close to a solder that would put B/C power to that wire but like I said... by design or due to faulty solder.
Guess I should also mention that if I put power to D I get voltage on D/C/B but not A. Since it's a dual gauge with two needles I'd thing that two of these inputs would correspond with each needle independently so there's that.
If anyone has any ideas on where to start or better yet where you would start please feel free to chime in. I'd really like to figure out if arduino can control this gauge prior to sending it off for a $600 restoration which is apparently the going rate for Aero gauge work? :o