I was playing around awhile back and ended up creating a way to show the fuel tank selector valve position on my Dynon Skyview (i.e. Left Tank, Right Tank, Both Tanks, and OFF).  

I ended up using some rare earth magnets from Harbor Freight, two small "bullet-type" reed relays, couple resistors (1 - 11k and 1 - 22k), 2 - Plastic/Threaded (10-32) Stand-Offs from Ace Hardware, 22AWG wire, and some epoxy for the project.

Pictures are available via Google Photos if interested:

http://bit.ly/2e4emfp

I also did a mock up of the circuit wiring/diagram as a sanity check for the EMS input pin/setup (P9 + P5/GND). Expected voltages match up to what the Dynon's EMS pages show too.

http://bit.ly/2dreYL1

FYI - The circuit diagram has two switches -- these are the reed relays. Toggling the switches will show the voltages that end up on the sensor input of the Dynon Skyview EMS module. The 10k resistor is the integrated resistor on the EMS unit.

Also, if curious as why only two reed relays were used, I had to be creative as I couldn't drill any additional holes and had to use the existing screwed holes in place for the fuel tank/valve selector. Ultimately, two worked out perfectly for showing all 4 states (i.e. Right, Left, Both, and Off).

I also set an alarm condition so if I ever accidentally leave the fuel selector in the off position, I'll get an alarm. Not that I've ever done that before!  

Don Honabach

Side note ... My need for this is the fuel selector is mounted in the spar web in-between my legs (with proper additional supports added).  I didn't want a center console and this was the next best location for me. I've been happy with "finger vision" up to now and access is incredibly easier and intuitive (for me at least).  That said, I wanted an additional indication to cross-check and ultimately to make life easier for another pilot that might not be comfortable with "finger vision".