Over the last two years I've designed and built three Arduino based soaring related devices.. They a 1) Tow Altitude Recorder with tow plane and ground units, 2) Cockpit Dual Battery Voltage & Temp Monitor, and 3)Trailer Lights Monitor.
The Tow Altitude Recorder tow plane unit records the takeoff time and the tow plane release altitude. The release altitude is recorded automatically based on the highest altitude reached for the tow or manually using the Record Altitude button. The recorded launch time and tow altitude is transmitted to the ground unit once the tow plane is at or below 1000 ft AGL. The ground unit displays the launch time and altitude of the two previous tows but also allows the user to scroll through all tows for the day. Links to photos of the tow plane and ground units are included in this post. Both the tow plane and ground units use backlit sunlight readable LCD displays.
The Cockpit Dual Battery Voltage & Temp Monitor measures and displays the avionics battery voltage and temperature inside the cockpit using a sunlight readable LCD display.
The Trailer Lights Monitor has a detector inserted in series with the trailer lights cable. The detector has a wireless connection to a display unit inside the vehicle which shows whether there is voltage on and current in each of the three trailer light circuits. The display consists of bi-colored LEDs which are off when the circuit is dead, Red for voltage only and Green for both voltage and current. Use of the monitor does not require any modifications to the car or trailer wiring.
If anyone is interested in building any of these devices I can provide a parts list, schematics, controller code, STL files for the enclosures, and more operational details. I do not have PCB layout files as I built mine using a proto board with wire wrap and solder connections.
Link to photo of Tow Altitude Recorder Units
https://drive.google.com/file/d/1tCA...ew?usp=sharing
Link to photo of Tow Plane Unit internal
https://drive.google.com/file/d/1Dig...ew?usp=sharing